In this interrupted case study, students examine the cooperative courtship behavior of long-tailed manakins. Males of the long-tailed form leks, areas in which males display for females in groups. Leks in this species consist of two to 11 males, with two males taking part in a cooperative song and dance display for females. After the cooperative display, only one of the males will mate with the female. Students consider a variety of possible explanations for the cooperation seen in this species, and use data from the original study to corroborate or reject hypotheses they formulate. The case provides a framework for a discussion of social behavior, including kin selection and reciprocal altruism, as well as for consideration of observational tests of hypotheses in field biology. Students conclude the case by making predictions about behaviors in other bird species, especially other species of manakins.