Prior research has produced mixed results on whether human social interaction can function as a reinforcer for dog behavior. However, that research used either short durations of social interaction or rapid, repeated trials such that satiation could have been a factor. We investigated whether two durations of social interaction (30 s or 4 s petting plus vocal praise) would maintain more responding than extinction, than each other, or than food. We limited each session to 10 trials and temporally spaced sessions within and across days. Both durations of social interaction produced more responding than extinction, but there was no difference in responding between the two social interaction durations. When we compared responding in food sessions to 30-s and 4-s social interaction sessions, we could not determine differences in responses emitted per session for two dogs due to ceiling effects, but the third dog doubled her responding when food was provided. Additionally, latencies in food sessions for all dogs were significantly lower than expected from a random sampling of latencies. Our results suggest both durations of social interaction can function as a reinforcer, especially when delivered sporadically, but they are still not as effective as food as a reinforcer for most dogs.