During the seven-day period from Aug. 3-9, Così Inc. brought about a 26.8-percent gain in its NRN Social 200 index score to land among the five largest weekly increases for the social engagement study.

Così joined four other brands that have appeared in a top weekly list already this summer, including two of the year’s steadiest performers, Papa Murphy’s Take ‘N Bake Pizza and Marie Callender’s Restaurant & Bakery. In this group of top weekly gainers, Facebook far and away was the medium where the chains engaged their audience.

In Così’s case, the brand benefited from accelerating the rate at which it posted new content, while the other top performers remained consistent in their efforts to engage fans anew each week. Their posting strategies ranged from contests to open-ended posts meant to spur more commenting — though several chains derived their best engagement from food shots for the week.

1. Old Chicago
Weekly percent change: +44.2%
Index score: 5.17

Old Chicago, which last landed in the top five weekly gainers for the Social 200 in early June, employs a diversified posting strategy for Facebook, where it gets the vast majority of its engagement. Trivia questions encourage lots of fan comments, and Old Chicago’s promotions around its ongoing World Beer Tour keep news fresh and updated on the brand’s page. Currently, a “Gridiron Mini Tour” is tying in to the upcoming college and pro-football seasons. But Old Chicago got the most engagement the second week of August with a post built around a food shot. The picture of its Ditka’s Polish Sliders earned the most likes and shares by far for the week, with more than 350 likes and nearly 30 shares.

2. Papa Murphy’s Take ‘N Bake Pizza
Weekly percent change: +33.4%
Index score: 13.07

Papa Murphy’s has appeared among the best weekly performers several times this summer, first for the spike in likes for its Facebook page upon the announcement of its Take ‘N Grill sweepstakes, and then for a few posts built upon pictures people have taken of themselves grilling the brand’s pizzas. During the second week of August, a food shot of its Cinnamon Wheel dessert drove more than 1,000 likes and earned nearly 75 shares.