diff --git a/include/sway/config.h b/include/sway/config.h
index be29082e..d07a71df 100644
--- a/include/sway/config.h
+++ b/include/sway/config.h
@@ -356,6 +356,7 @@ struct sway_config {
 		struct input_config *input_config;
 		struct seat_config *seat_config;
 		struct sway_seat *seat;
+		swayc_t *current_container;
 	} handler_context;
 };
 
diff --git a/include/sway/container.h b/include/sway/container.h
index 9a5e312b..a99e2694 100644
--- a/include/sway/container.h
+++ b/include/sway/container.h
@@ -145,4 +145,6 @@ swayc_t *swayc_parent_by_type(swayc_t *container, enum swayc_types type);
 swayc_t *swayc_at(swayc_t *parent, double lx, double ly,
 		struct wlr_surface **surface, double *sx, double *sy);
 
+void container_map(swayc_t *container, void (*f)(swayc_t *view, void *data), void *data);
+
 #endif
diff --git a/include/sway/criteria.h b/include/sway/criteria.h
new file mode 100644
index 00000000..c5ed9857
--- /dev/null
+++ b/include/sway/criteria.h
@@ -0,0 +1,42 @@
+#ifndef _SWAY_CRITERIA_H
+#define _SWAY_CRITERIA_H
+
+#include "container.h"
+#include "list.h"
+
+/**
+ * Maps criteria (as a list of criteria tokens) to a command list.
+ *
+ * A list of tokens together represent a single criteria string (e.g.
+ * '[class="abc" title="xyz"]' becomes two criteria tokens).
+ *
+ * for_window: Views matching all criteria will have the bound command list
+ * executed on them.
+ *
+ * Set via `for_window <criteria> <cmd list>`.
+ */
+struct criteria {
+	list_t *tokens; // struct crit_token, contains compiled regex.
+	char *crit_raw; // entire criteria string (for logging)
+
+	char *cmdlist;
+};
+
+int criteria_cmp(const void *item, const void *data);
+void free_criteria(struct criteria *crit);
+
+// Pouplate list with crit_tokens extracted from criteria string, returns error
+// string or NULL if successful.
+char *extract_crit_tokens(list_t *tokens, const char *criteria);
+
+// Returns list of criteria that match given container. These criteria have
+// been set with `for_window` commands and have an associated cmdlist.
+list_t *criteria_for(swayc_t *cont);
+
+// Returns a list of all containers that match the given list of tokens.
+list_t *container_for(list_t *tokens);
+
+// Returns true if any criteria in the given list matches this container
+bool criteria_any(swayc_t *cont, list_t *criteria);
+
+#endif
diff --git a/sway/commands.c b/sway/commands.c
index 28943963..c1e25c5f 100644
--- a/sway/commands.c
+++ b/sway/commands.c
@@ -8,6 +8,7 @@
 #include <json-c/json.h>
 #include "sway/commands.h"
 #include "sway/config.h"
+#include "sway/criteria.h"
 #include "sway/security.h"
 #include "sway/input/input-manager.h"
 #include "stringop.h"
@@ -201,9 +202,41 @@ struct cmd_results *handle_command(char *_exec) {
 	char *head = exec;
 	char *cmdlist;
 	char *cmd;
+	list_t *containers = NULL;
 
 	head = exec;
 	do {
+		// Extract criteria (valid for this command list only).
+		bool has_criteria = false;
+		if (*head == '[') {
+			has_criteria = true;
+			++head;
+			char *criteria_string = argsep(&head, "]");
+			if (head) {
+				++head;
+				list_t *tokens = create_list();
+				char *error;
+
+				if ((error = extract_crit_tokens(tokens, criteria_string))) {
+					wlr_log(L_DEBUG, "criteria string parse error: %s", error);
+					results = cmd_results_new(CMD_INVALID, criteria_string,
+						"Can't parse criteria string: %s", error);
+					free(error);
+					free(tokens);
+					goto cleanup;
+				}
+				containers = container_for(tokens);
+
+				free(tokens);
+			} else {
+				if (!results) {
+					results = cmd_results_new(CMD_INVALID, criteria_string, "Unmatched [");
+				}
+				goto cleanup;
+			}
+			// Skip leading whitespace
+			head += strspn(head, whitespace);
+		}
 		// Split command list
 		cmdlist = argsep(&head, ";");
 		cmdlist += strspn(cmdlist, whitespace);
@@ -236,16 +269,35 @@ struct cmd_results *handle_command(char *_exec) {
 				free_argv(argc, argv);
 				goto cleanup;
 			}
-			struct cmd_results *res = handler->handle(argc-1, argv+1);
-			if (res->status != CMD_SUCCESS) {
-				free_argv(argc, argv);
-				if (results) {
-					free_cmd_results(results);
+
+			if (!has_criteria) {
+				config->handler_context.current_container = NULL;
+				struct cmd_results *res = handler->handle(argc-1, argv+1);
+				if (res->status != CMD_SUCCESS) {
+					free_argv(argc, argv);
+					if (results) {
+						free_cmd_results(results);
+					}
+					results = res;
+					goto cleanup;
+				}
+				free_cmd_results(res);
+			} else {
+				wlr_log(L_DEBUG, "@@ running command on containers");
+				for (int i = 0; i < containers->length; ++i) {
+					config->handler_context.current_container = containers->items[i];
+					struct cmd_results *res = handler->handle(argc-1, argv+1);
+					if (res->status != CMD_SUCCESS) {
+						free_argv(argc, argv);
+						if (results) {
+							free_cmd_results(results);
+						}
+						results = res;
+						goto cleanup;
+					}
+					free_cmd_results(res);
 				}
-				results = res;
-				goto cleanup;
 			}
-			free_cmd_results(res);
 			free_argv(argc, argv);
 		} while(cmdlist);
 	} while(head);
diff --git a/sway/commands/kill.c b/sway/commands/kill.c
index 4bbf94e5..f0e3722a 100644
--- a/sway/commands/kill.c
+++ b/sway/commands/kill.c
@@ -15,7 +15,13 @@ struct cmd_results *cmd_kill(int argc, char **argv) {
 		return cmd_results_new(CMD_FAILURE, NULL, "no seat context given");
 	}
 
-	struct sway_view *view = seat->focus->sway_view;
+	struct sway_view *view = NULL;
+
+	if (config->handler_context.current_container) {
+		view = config->handler_context.current_container->sway_view;
+	} else {
+		view = seat->focus->sway_view;
+	}
 
 	if (view->iface.close) {
 		view->iface.close(view);
diff --git a/sway/criteria.c b/sway/criteria.c
new file mode 100644
index 00000000..c15f6354
--- /dev/null
+++ b/sway/criteria.c
@@ -0,0 +1,413 @@
+#define _XOPEN_SOURCE 700
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <pcre.h>
+#include "sway/criteria.h"
+#include "sway/container.h"
+#include "sway/config.h"
+#include "sway/view.h"
+#include "stringop.h"
+#include "list.h"
+#include "log.h"
+
+enum criteria_type { // *must* keep in sync with criteria_strings[]
+	CRIT_APP_ID,
+	CRIT_CLASS,
+	CRIT_CON_ID,
+	CRIT_CON_MARK,
+	CRIT_FLOATING,
+	CRIT_ID,
+	CRIT_INSTANCE,
+	CRIT_TILING,
+	CRIT_TITLE,
+	CRIT_URGENT,
+	CRIT_WINDOW_ROLE,
+	CRIT_WINDOW_TYPE,
+	CRIT_WORKSPACE,
+	CRIT_LAST
+};
+
+static const char * const criteria_strings[CRIT_LAST] = {
+	[CRIT_APP_ID] = "app_id",
+	[CRIT_CLASS] = "class",
+	[CRIT_CON_ID] = "con_id",
+	[CRIT_CON_MARK] = "con_mark",
+	[CRIT_FLOATING] = "floating",
+	[CRIT_ID] = "id",
+	[CRIT_INSTANCE] = "instance",
+	[CRIT_TILING] = "tiling",
+	[CRIT_TITLE] = "title",
+	[CRIT_URGENT] = "urgent", // either "latest" or "oldest" ...
+	[CRIT_WINDOW_ROLE] = "window_role",
+	[CRIT_WINDOW_TYPE] = "window_type",
+	[CRIT_WORKSPACE] = "workspace"
+};
+
+/**
+ * A single criteria token (ie. value/regex pair),
+ * e.g. 'class="some class regex"'.
+ */
+struct crit_token {
+	enum criteria_type type;
+	pcre *regex;
+	char *raw;
+};
+
+static void free_crit_token(struct crit_token *crit) {
+	pcre_free(crit->regex);
+	free(crit->raw);
+	free(crit);
+}
+
+static void free_crit_tokens(list_t *crit_tokens) {
+	for (int i = 0; i < crit_tokens->length; i++) {
+		free_crit_token(crit_tokens->items[i]);
+	}
+	list_free(crit_tokens);
+}
+
+// Extracts criteria string from its brackets. Returns new (duplicate)
+// substring.
+static char *criteria_from(const char *arg) {
+	char *criteria = NULL;
+	if (*arg == '[') {
+		criteria = strdup(arg + 1);
+	} else {
+		criteria = strdup(arg);
+	}
+
+	int last = strlen(criteria) - 1;
+	if (criteria[last] == ']') {
+		criteria[last] = '\0';
+	}
+	return criteria;
+}
+
+// Return instances of c found in str.
+static int countchr(char *str, char c) {
+	int found = 0;
+	for (int i = 0; str[i]; i++) {
+		if (str[i] == c) {
+			++found;
+		}
+	}
+	return found;
+}
+
+// criteria_str is e.g. '[class="some class regex" instance="instance name"]'.
+//
+// Will create array of pointers in buf, where first is duplicate of given
+// string (must be freed) and the rest are pointers to names and values in the
+// base string (every other, naturally). argc will be populated with the length
+// of buf.
+//
+// Returns error string or NULL if successful.
+static char *crit_tokens(int *argc, char ***buf, const char * const criteria_str) {
+	wlr_log(L_DEBUG, "Parsing criteria: '%s'", criteria_str);
+	char *base = criteria_from(criteria_str);
+	char *head = base;
+	char *namep = head; // start of criteria name
+	char *valp = NULL; // start of value
+
+	// We're going to place EOS markers where we need to and fill up an array
+	// of pointers to the start of each token (either name or value).
+	int pairs = countchr(base, '=');
+	int max_tokens = pairs * 2 + 1; // this gives us at least enough slots
+
+	char **argv = *buf = calloc(max_tokens, sizeof(char*));
+	argv[0] = base; // this needs to be freed by caller
+	bool quoted = true;
+
+	*argc = 1; // uneven = name, even = value
+	while (*head && *argc < max_tokens) {
+		if (namep != head && *(head - 1) == '\\') {
+			// escaped character: don't try to parse this
+		} else if (*head == '=' && namep != head) {
+			if (*argc % 2 != 1) {
+				// we're not expecting a name
+				return strdup("Unable to parse criteria: "
+					"Found out of place equal sign");
+			} else {
+				// name ends here
+				char *end = head; // don't want to rewind the head
+				while (*(end - 1) == ' ') {
+					--end;
+				}
+				*end = '\0';
+				if (*(namep) == ' ') {
+					namep = strrchr(namep, ' ') + 1;
+				}
+				argv[*argc] = namep;
+				*argc += 1;
+			}
+		} else if (*head == '"') {
+			if (*argc % 2 != 0) {
+				// we're not expecting a value
+				return strdup("Unable to parse criteria: "
+					"Found quoted value where it was not expected");
+			} else if (!valp) { // value starts here
+				valp = head + 1;
+				quoted = true;
+			} else {
+				// value ends here
+				argv[*argc] = valp;
+				*argc += 1;
+				*head = '\0';
+				valp = NULL;
+				namep = head + 1;
+			}
+		} else if (*argc % 2 == 0 && *head != ' ') {
+			// parse unquoted values
+			if (!valp) {
+				quoted = false;
+				valp = head;  // value starts here
+			}
+		} else if (valp && !quoted && *head == ' ') {
+			// value ends here
+			argv[*argc] = valp;
+			*argc += 1;
+			*head = '\0';
+			valp = NULL;
+			namep = head + 1;
+		}
+		head++;
+	}
+
+	// catch last unquoted value if needed
+	if (valp && !quoted && !*head) {
+		argv[*argc] = valp;
+		*argc += 1;
+	}
+
+	return NULL;
+}
+
+// Returns error string on failure or NULL otherwise.
+static char *parse_criteria_name(enum criteria_type *type, char *name) {
+	*type = CRIT_LAST;
+	for (int i = 0; i < CRIT_LAST; i++) {
+		if (strcmp(criteria_strings[i], name) == 0) {
+			*type = (enum criteria_type) i;
+			break;
+		}
+	}
+	if (*type == CRIT_LAST) {
+		const char *fmt = "Criteria type '%s' is invalid or unsupported.";
+		int len = strlen(name) + strlen(fmt) - 1;
+		char *error = malloc(len);
+		snprintf(error, len, fmt, name);
+		return error;
+	} else if (*type == CRIT_URGENT || *type == CRIT_WINDOW_ROLE ||
+			*type == CRIT_WINDOW_TYPE) {
+		// (we're just being helpful here)
+		const char *fmt = "\"%s\" criteria currently unsupported, "
+			"no window will match this";
+		int len = strlen(fmt) + strlen(name) - 1;
+		char *error = malloc(len);
+		snprintf(error, len, fmt, name);
+		return error;
+	}
+	return NULL;
+}
+
+// Returns error string on failure or NULL otherwise.
+static char *generate_regex(pcre **regex, char *value) {
+	const char *reg_err;
+	int offset;
+
+	*regex = pcre_compile(value, PCRE_UTF8 | PCRE_UCP, &reg_err, &offset, NULL);
+
+	if (!*regex) {
+		const char *fmt = "Regex compilation (for '%s') failed: %s";
+		int len = strlen(fmt) + strlen(value) + strlen(reg_err) - 3;
+		char *error = malloc(len);
+		snprintf(error, len, fmt, value, reg_err);
+		return error;
+	}
+	return NULL;
+}
+
+// Test whether the criterion corresponds to the currently focused window
+static bool crit_is_focused(const char *value) {
+	return !strcmp(value, "focused") || !strcmp(value, "__focused__");
+}
+
+// Populate list with crit_tokens extracted from criteria string, returns error
+// string or NULL if successful.
+char *extract_crit_tokens(list_t *tokens, const char * const criteria) {
+	int argc;
+	char **argv = NULL, *error = NULL;
+	if ((error = crit_tokens(&argc, &argv, criteria))) {
+		goto ect_cleanup;
+	}
+	for (int i = 1; i + 1 < argc; i += 2) {
+		char* name = argv[i], *value = argv[i + 1];
+		struct crit_token *token = calloc(1, sizeof(struct crit_token));
+		token->raw = strdup(value);
+
+		if ((error = parse_criteria_name(&token->type, name))) {
+			free_crit_token(token);
+			goto ect_cleanup;
+		} else if (token->type == CRIT_URGENT || crit_is_focused(value)) {
+			wlr_log(L_DEBUG, "%s -> \"%s\"", name, value);
+			list_add(tokens, token);
+		} else if((error = generate_regex(&token->regex, value))) {
+			free_crit_token(token);
+			goto ect_cleanup;
+		} else {
+			wlr_log(L_DEBUG, "%s -> /%s/", name, value);
+			list_add(tokens, token);
+		}
+	}
+ect_cleanup:
+	free(argv[0]); // base string
+	free(argv);
+	return error;
+}
+
+static int regex_cmp(const char *item, const pcre *regex) {
+	return pcre_exec(regex, NULL, item, strlen(item), 0, 0, NULL, 0);
+}
+
+// test a single view if it matches list of criteria tokens (all of them).
+static bool criteria_test(swayc_t *cont, list_t *tokens) {
+	if (cont->type != C_VIEW) {
+		return false;
+	}
+	struct sway_view *view = cont->sway_view;
+
+	int matches = 0;
+	for (int i = 0; i < tokens->length; i++) {
+		struct crit_token *crit = tokens->items[i];
+		switch (crit->type) {
+		case CRIT_CLASS: // TODO
+			break;
+		case CRIT_CON_ID: {
+			char *endptr;
+			size_t crit_id = strtoul(crit->raw, &endptr, 10);
+
+			if (*endptr == 0 && cont->id == crit_id) {
+				++matches;
+			}
+			break;
+		}
+		case CRIT_CON_MARK: // TODO
+			break;
+		case CRIT_FLOATING: // TODO
+			break;
+		case CRIT_ID: // TODO
+			break;
+		case CRIT_APP_ID:
+			if (!view->iface.get_prop) {
+				break;
+			}
+
+			const char *app_id =
+				cont->sway_view->iface.get_prop(view, VIEW_PROP_APP_ID);
+
+			if (!app_id) {
+				break;
+			}
+			
+			if (crit->regex && regex_cmp(app_id, crit->regex) == 0) {
+				matches++;
+			}
+			break;
+		case CRIT_INSTANCE: // TODO
+			break;
+		case CRIT_TILING: // TODO
+			break;
+		case CRIT_TITLE:
+			if (!cont->name) {
+				// ignore
+			} else if (crit->regex && regex_cmp(cont->name, crit->regex) == 0) {
+				matches++;
+			}
+			break;
+		case CRIT_URGENT: // "latest" or "oldest"
+			break;
+		case CRIT_WINDOW_ROLE:
+			break;
+		case CRIT_WINDOW_TYPE:
+			break;
+		case CRIT_WORKSPACE: // TODO
+			break;
+		default:
+			sway_abort("Invalid criteria type (%i)", crit->type);
+			break;
+		}
+	}
+	return matches == tokens->length;
+}
+
+int criteria_cmp(const void *a, const void *b) {
+	if (a == b) {
+		return 0;
+	} else if (!a) {
+		return -1;
+	} else if (!b) {
+		return 1;
+	}
+	const struct criteria *crit_a = a, *crit_b = b;
+	int cmp = lenient_strcmp(crit_a->cmdlist, crit_b->cmdlist);
+	if (cmp != 0) {
+		return cmp;
+	}
+	return lenient_strcmp(crit_a->crit_raw, crit_b->crit_raw);
+}
+
+void free_criteria(struct criteria *crit) {
+	if (crit->tokens) {
+		free_crit_tokens(crit->tokens);
+	}
+	if (crit->cmdlist) {
+		free(crit->cmdlist);
+	}
+	if (crit->crit_raw) {
+		free(crit->crit_raw);
+	}
+	free(crit);
+}
+
+bool criteria_any(swayc_t *cont, list_t *criteria) {
+	for (int i = 0; i < criteria->length; i++) {
+		struct criteria *bc = criteria->items[i];
+		if (criteria_test(cont, bc->tokens)) {
+			return true;
+		}
+	}
+	return false;
+}
+
+list_t *criteria_for(swayc_t *cont) {
+	list_t *criteria = config->criteria, *matches = create_list();
+	for (int i = 0; i < criteria->length; i++) {
+		struct criteria *bc = criteria->items[i];
+		if (criteria_test(cont, bc->tokens)) {
+			list_add(matches, bc);
+		}
+	}
+	return matches;
+}
+
+struct list_tokens {
+	list_t *list;
+	list_t *tokens;
+};
+
+static void container_match_add(swayc_t *container, struct list_tokens *list_tokens) {
+	if (criteria_test(container, list_tokens->tokens)) {
+		list_add(list_tokens->list, container);
+	}
+}
+
+list_t *container_for(list_t *tokens) {
+	struct list_tokens list_tokens = (struct list_tokens){create_list(), tokens};
+
+	container_map(&root_container, (void (*)(swayc_t *, void *))container_match_add, &list_tokens);
+
+	// TODO look in the scratchpad
+	
+	return list_tokens.list;
+}
diff --git a/sway/meson.build b/sway/meson.build
index d5dead42..46d79d44 100644
--- a/sway/meson.build
+++ b/sway/meson.build
@@ -38,6 +38,7 @@ sway_sources = files(
 	'config/output.c',
 	'config/seat.c',
 	'config/input.c',
+	'criteria.c',
 	'ipc-json.c',
 	'ipc-server.c',
 	'desktop/output.c',
@@ -51,6 +52,7 @@ sway_sources = files(
 )
 
 sway_deps = [
+	pcre,
 	pixman,
 	wayland_server,
 	jsonc,
diff --git a/sway/tree/container.c b/sway/tree/container.c
index d241f69a..e224539f 100644
--- a/sway/tree/container.c
+++ b/sway/tree/container.c
@@ -321,3 +321,25 @@ swayc_t *swayc_at(swayc_t *parent, double lx, double ly,
 
 	return NULL;
 }
+
+void container_map(swayc_t *container, void (*f)(swayc_t *view, void *data), void *data) {
+	if (container) {
+		int i;
+		if (container->children)  {
+			for (i = 0; i < container->children->length; ++i) {
+				swayc_t *child = container->children->items[i];
+				container_map(child, f, data);
+			}
+		}
+		// TODO
+		/*
+		if (container->floating) {
+			for (i = 0; i < container->floating->length; ++i) {
+				swayc_t *child = container->floating->items[i];
+				container_map(child, f, data);
+			}
+		}
+		*/
+		f(container, data);
+	}
+}