3 Chen, J. Geyer, W. Dugan, C. Muller, M. Guy, I. 2009 ACM SIGCHI Conference on Human Factors in Computing Systems <p>This paper studies people recommendations designed to help users find known, offline contacts and discover new friends on social networking sites. We evaluated four  recommender  algorithms in an enterprise social networking site using a personalized survey of 500 users and a field study of 3,000 users. We found all algorithms effective in expanding users’ friend lists. Algorithms based on social network information were able to produce better-received recommendations and find more known contacts for users, while algorithms using similarity of user-created content were stronger in discovering new friends. We also collected qualitative feedback from our survey users and draw several meaningful design implications.</p>