diff --git a/src/rvprof_core.c b/src/rvprof_core.c
index bec919d..0528f4f 100644
--- a/src/rvprof_core.c
+++ b/src/rvprof_core.c
@@ -55,7 +55,6 @@ void rvprof_init(const char* output_file){
 
     rvprof_symbols_init(g_rvprof.config.program_name); // in case symbol resolution fails, just addresses are printed later
 
-
     // rest of global state
     g_rvprof.stack_ptr = -1;
     g_rvprof.initialized = 1;
@@ -86,3 +85,53 @@ void rvprof_set_program_name(const char* program_name){
     }
 }
 
+void rvprof_region_begin(const char* name){
+    // auto-initialize with default settings if not yet initialized
+    if (!g_rvprof.initialized){
+        rvprof_init(NULL); 
+        g_rvprof.auto_initialized = 1;
+    }
+
+    g_rvprof.stack_ptr++;
+    if(region_array_ensure_capacity(&g_rvprof.regions, g_rvprof.stack_ptr) < 0) {
+        g_rvprof.stack_ptr--;
+        return;
+    }
+
+    region_t* region = &g_rvprof.regions.data[g_rvprof.stack_ptr];
+
+    // initialize region
+    strncpy(region->name, name, MAX_NAME_LEN-1);
+    region->name[MAX_NAME_LEN-1] = '\0';
+    region->depth = g_rvprof.stack_ptr;
+    region->child_time = 0;
+    region->child_cycles = 0;
+    region->func_addr = NULL;
+    region->stack_id = rvprof_stats_get_or_create_stack_id;
+
+    // look up or create ID for region
+    const char* caller;
+    if(g_rvprof.stack_ptr > 0){
+        caller = g_rvprof.regions.data[g_rvprof.stack_ptr-1].name;
+    } else {
+        caller = "---";
+    }
+    region->function_id = rvprof_stats_find_or_create_function(name, caller);
+
+    // increase call count for ID and record call stack
+    if (region->function_id >= 0){
+        g_rvprof.functions.data[region->function_id].call_count++;
+        rvprof_stats_add_stack_id_to_function(region->function_id, region->stack_id);
+        if (g_rvprof.config.merge_regions){
+            rvprof_stats_add_caller_to_function(region->function_id, caller);
+        }
+
+    }
+
+
+    // start timing
+    region->start_time_ns = rvprof_timing_get_current();
+    region->start_cycles = rvprof_timing_get_cycles();
+
+}
+