Individual phenotypes may be influenced by the social environment, which is itself a function of the phenotypes of a set of socially-interacting individuals. We have been using theoretical models and experiments with a cooperatively-breeding African cichlid fish, Neolamprologus pulcher, to examine social behavior, and selection on social behavior, in the context of interacting phenotypes. I will present results from two sets of studies. In the first, we tested the general hypotheses that, in N pulcher groups, there is conflict between the dominant male and female over the presence and behavior of subordinate “helpers” that provide care for all group offspring but may be reproductive competitors, and that, as a consequence, the behavior of subordinate helpers in the group depends, in part, on the resolution of conflict between the dominant pair. We also examined whether individual variation in subordinate male behavior (or subordinate ”˜personality’) indirectly influenced conflict between the dominant pair. We found that consistently helpful subordinate males were associated with reduced conflict between dominant males and females. In a second set of studies, we used evolutionary dynamic models to investigate the role of partner control on the phenotypic make-up of groups and selection on behavior that is costly to social partners. We find that, when individual variation in behavior exists or when behavior is plastic with respect to the social environment, strategies of partner control can result in non-random association between costliness and willingness to engage in partner control. This non-random association results in social selection for increased investment in partner control and reduced costliness relative to a well-mixed model.