A review by the ManyPrimates project confirmed long-standing beliefs about the field of primate cognition. Namely, research is driven by a handful of species, often from the same study site, and inferences are limited by small sample sizes. However, the review did not address another common practice in primate cognition: sampling only adults. Whereas adult data have been useful for comparisons to human literature for understanding cognitive abilities on an evolutionary timescale, these studies do not allow investigators to ask questions about the developmental processes underlying primate cognition. The purpose of this secondary systematic review was to provide a state of the field on developmental primate cognition by answering the following questions about recent publications using the ManyPrimates dataset: (1) how often investigators sampled infants and/or juveniles separately from adults; (2) when infants and/or juveniles were included with adults, how often was age analyzed statistically; (3) how often were studies longitudinal; (4) what topics have been studied; and (5) what techniques have been used. Results revealed that the typical recent primate cognition study did not incorporate development. Practical challenges that may preclude investigators from pursuing developmental research questions in primate cognition are discussed with recommendations to guide future research.