We develop a unified empirical framework for child development which nests the key features of two previously parallel research programs, the Child Development literature and the Education Production Function literature. Our framework allows for mis-measured cognitive and non-cognitive skills, classroom effects, parental influences, and complementarities/interactions. Although both are important, we estimate that differential parental investments are the more important source of end-of-kindergarten inequality than classroom quality. Higher quality classrooms and home investments have a larger effect on children entering kindergarten with skill deficits, a negative complementarity. Our estimated model replicates patterns by excluded race and family income variables and experimental results from the Tennessee STAR experiment. Finally, we find that the estimated classroom quality from standard value-added models would systematically be confounded with the student selection into classrooms based on their (omitted) non-cognitive skills and their home quality. [This paper was issued in July 2019 and revised in January 2020.]