diff --git a/context.core.inc b/context.core.inc
index f169b6f..5498083 100644
--- a/context.core.inc
+++ b/context.core.inc
@@ -99,15 +99,6 @@ function context_theme_registry_alter(&$theme_registry) {
   if (!in_array('context_page_alter', $theme_registry['page']['preprocess functions'])) {
     array_unshift($theme_registry['page']['preprocess functions'], 'context_page_alter');
   }
-  // Reroute theme_blocks() through context_blocks to determine block
-  // visibility by context. Only override theme_blocks() if a theme
-  // has not overridden it. It is the responsibility of any themes
-  // implementing theme_blocks() to take advantage of context block
-  // visibility on their own.
-  if (!isset($theme_registry['blocks']['type']) || !in_array($theme_registry['blocks']['type'], array('base_theme_engine', 'theme_engine')) && !isset($theme_registry['blocks']['file'])) {
-    unset($theme_registry['blocks']['preprocess functions']);
-    $theme_registry['blocks']['function'] = 'context_blocks';
-  }
 }
 
 /**
@@ -223,20 +214,6 @@ function context_user($op, &$edit, &$account, $category = NULL) {
 }
 
 /**
- * BLOCK HANDLING =====================================================
- */
-
-/**
- * This override of theme_blocks() is called because of an alter of the
- * theme registry. See context_theme_registry_alter().
- */
-function context_blocks($region) {
-  if ($plugin = context_get_plugin('reaction', 'block')) {
-    return $plugin->execute($region);
-  }
-}
-
-/**
  * THEME FUNCTIONS & RELATED ==========================================
  */
 
@@ -284,6 +261,20 @@ function context_links($reset = FALSE) {
 function context_page_alter(&$vars) {
   module_invoke_all('context_page_condition');
   module_invoke_all('context_page_reaction');
+
+  // Block handling
+  if ($plugin = context_get_plugin('reaction', 'block')) {
+    global $theme;
+    // Populate all block regions.
+    $regions = system_region_list($theme);
+    // Load all region content assigned via blocks.
+    foreach (array_keys($regions) as $region) {
+      // Prevent left and right regions from rendering blocks when 'show_blocks' == FALSE.
+      if (!(!$vars['show_blocks'] && ($region == 'left' || $region == 'right'))) {
+        drupal_set_content($region, $plugin->execute($region));
+      }
+    }
+  }
 }
 
 /**
diff --git a/plugins/context_reaction_block.inc b/plugins/context_reaction_block.inc
index 7aaedae..ef6188e 100644
--- a/plugins/context_reaction_block.inc
+++ b/plugins/context_reaction_block.inc
@@ -305,10 +305,7 @@ class context_reaction_block extends context_reaction {
         }
       }
     }
-
-    // Get core blocks only if enabled.
-    $blocks = !variable_get('context_reaction_block_disable_core', FALSE) ? block_list($region) : array();
-    $blocks = array_merge($blocks, $context_blocks[$region]);
+    $blocks = $context_blocks[$region];
 
     // Only include empty blocks if all regions should be shown or there are
     // non-empty blocks in the same region.