The elderly face serious social, environmental, and physical constraints that impact their well-being. Some of the most serious of these are shrinking social connections, limitations in building new relationships, and diminished health. To address these issues, we have designed an augmented dancing environment that allows elders to select dance sequences from well-known movies and dance along with them. The goal of DanceAlong is twofold: (1) to provide entertainment and exercise for each individual user and (2) to promote social engagement within the group. We deployed DanceAlong in a cultural celebration at a senior community center and conducted evaluations. In this paper, we present the design process of DanceAlong, evaluations of DanceAlong, and design guidelines for creating similar interactive systems for the elderly.