The study of cooperative breeding in birds has a long history in the New World tropics, beginning with Alexander Skutch’s seminal observations of helpers at the nest. Recent studies of Neotropical birds have revealed a diversity of cooperative systems, ranging from small family groups to complex societies composed of relatives and immigrants. This chapter focuses on the communally breeding cuckoos—the anis and their allies—which breed in social groups with several unrelated co-breeders. Data from a long-term field project on greater anis in Panama sheds light on the selective pressures shaping reproductive strategies, including effects on reproductive fitness, mating and parental care patterns, and alternative reproductive tactics such as conspecific brood parasitism.