In primates, male reproductive success is often facilitated by dominance rank. While we have a good understanding of the ultimate benefits that dominance rank provides males, we know less about how male physiology and phenotypes change as males undergo changes in dominance rank. In this seminar, I will discuss our ongoing research on the hormonal, morphological, olfactory, and behavioral correlates of male rank acquisition in white faced-capuchins. Changes in male dominance rank are also associated with high rates of infanticide, which produces extreme sexual conflict. Females have evolved strategies to reduce the occurrence and/or costs of infanticide to female reproductive success. I will discuss our exploration of one potential female strategy, the Bruce effect - the termination of pregnancy in response to exposure to non-sire males.