diff --git a/newspack-theme/functions.php b/newspack-theme/functions.php
index f27df7702..d38ec8347 100755
--- a/newspack-theme/functions.php
+++ b/newspack-theme/functions.php
@@ -699,6 +699,80 @@ function newspack_coauthors_in_rss( $the_author ) {
 }
 add_filter( 'the_author', 'newspack_coauthors_in_rss' );
 
+/**
+ * Determine minimum theme breakpoint, below which responsive Ads media queries should not have a min-width.
+ *
+ * @param array  $media_queries An array of objects, one for each size, with width|height|min_width|min_height.
+ * @param string $placement ID of the ad placement.
+ * @param string $context Optional second string describing the ad placement. For Widget placements, the ID of the Widget.
+ * @return array The correct array of media query data.
+ */
+function newspack_theme_newspack_ads_media_queries( $media_queries, $placement, $context ) {
+	if ( 'newspack_ads_widget' === $placement && strpos( $context, 'scaip' ) === 0 ) {
+		switch ( get_page_template_slug() ) {
+			case 'single-wide.php':
+				foreach ( $media_queries as $index => &$media_query ) {
+					$next_media_query = ( count( $media_queries ) > $index + 1 ) ? $media_queries[ $index + 1 ] : null;
+					if ( intval( $media_query['width'] ) > 1200 ) {
+						$media_query['min_width'] = null;
+						$media_query['max_width'] = null;
+					} else {
+						$media_query['min_width'] = ceil( intval( $media_query['width'] ) / 0.9 );
+						if ( $next_media_query['width'] && $next_media_query['width'] <= 1200 ) {
+							$media_query['max_width'] = ceil( $next_media_query['width'] / 0.9 - 1 );
+						} else {
+							$media_query['max_width'] = null;
+						}
+					}
+				}
+				break;
+			case 'single-feature.php':
+			default:
+				foreach ( $media_queries as $index => &$media_query ) {
+					$next_media_query = ( count( $media_queries ) > $index + 1 ) ? $media_queries[ $index + 1 ] : null;
+					if ( intval( $media_query['width'] ) > 780 ) {
+						$media_query['min_width'] = null;
+						$media_query['max_width'] = null;
+					} else if ( intval( $media_query['width'] ) > ceil( 782 * 0.585 ) ) {
+						$media_query['min_width'] = ceil( intval( $media_query['width'] ) / 0.585 );
+						if ( $next_media_query['width'] && $next_media_query['width'] <= 780 ) {
+							$media_query['max_width'] = ceil( $next_media_query['width'] / 0.585 - 1 );
+						} else {
+							$media_query['max_width'] = null;
+						}
+					} else {
+						$media_query['min_width'] = ceil( intval( $media_query['width'] ) / 0.9 );
+						if ( $next_media_query['width'] && $next_media_query['width'] <= 780 ) {
+							$media_query['max_width'] = ceil( $next_media_query['width'] / 0.585 - 1 );
+						} else {
+							$media_query['max_width'] = null;
+						}
+					}
+				}
+				break;
+		}
+	}
+	return $media_queries;
+}
+add_filter( 'newspack_ads_media_queries', 'newspack_theme_newspack_ads_media_queries', 10, 3 );
+
+/**
+ * Should a particular Ad deployment use responsive placement.
+ *
+ * @param boolean $responsive Default value of whether to use responsive placement.
+ * @param string  $placement ID of the ad placement.
+ * @param string  $context Optional second string describing the ad placement. For Widget placements, the ID of the Widget.
+ * @return boolean Whether to use responsive placement.
+ */
+function newspack_theme_newspack_ads_maybe_use_responsive_placement( $responsive, $placement, $context ) {
+	// Apply Responsive placement to widgets using Super Cool Ad Inserter.
+	if ( 'newspack_ads_widget' === $placement && strpos( $context, 'scaip' ) === 0 ) {
+		return true;
+	}
+	return $responsive;
+}
+add_filter( 'newspack_ads_maybe_use_responsive_placement', 'newspack_theme_newspack_ads_maybe_use_responsive_placement', 10, 3 );
+
 /**
  * Notify about child theme deprecation.
  * TODO: Remove after child theme code is removed.