Google Inc. is letting marketers turn the content they post on the Google Plus social network into ads that appear across web sites in the Google Display Network.

The search giant this week announced that it is testing an ad format called +Post ads that, with a few clicks, allow a brand to feature previously posted Google Plus content, like a photo or video, in a display ad that can run across the more than 2 million sites in the Google Display Network. Toyota Motor Sales USA Inc. and Mondelez International’s Ritz Crackers brand are among the brands participating in the test.

“This lets brands think of the entire web as their social stream,” writes Eran Arkin, Google product manager, in a Google Plus post. That stands in contrast to Facebook’s various ad formats which, with few exceptions, are limited to the social network’s ecosystem.

Because the ads let a Google Plus user interact with the expandable ad—for example, by leaving a comment or launching a Hangout, the social network’s video conference tool—they should have higher click-through and engagement rates than other ad formats, Arkin suggests. Early tests show that expansion rates, a measure of how often a consumer clicks to see all of an expandable ad, are roughly 50% higher than the industry average for rich media ad units.

Google says that it is opening up the test to more advertisers and that it plans to continue collecting feedback from brands and users.

The move is the latest step by Google to leverage Google Plus to make its ad units and other web properties more social. For example, in October Google announced plans to feature users’ names, photos and comments in ads across the Internet in a new program it calls “Shared Endorsements.”