In this article, I explore two epistemologies for theorizing infancy and treating autism--infant and child psychoanalysis expounded by Frances Tustin and colleagues and developmental psychology and developmental neuroscience. I address two main issues: (a) how early psychoanalytic insights informed empirical developments and theoretical scholarship in both infant psychoanalysis and developmental psychology, and (b) how the study of infant development within psychoanalysis has been derailed by faulty theorizing and failure to incorporate scientific scholarship on infant development into their theories and practice. First, I review current research on infancy including psychoanalytic contributions that have incorporated scientific methods and evidence. I then juxtapose this work with Frances Tustin's theory of autism as an exemplar of the problematic theorizing about infant development that remains unchallenged, even today, in some psychoanalytic circles, and how that theory is operationalized in treatment. I discuss possible reasons for the failure to revise theory and therapeutic practice and the adherence to faulty perceptions of "successful" therapeutic outcome. Despite these derailments, I conclude that a marriage of science and psychoanalysis (that is convergent with developmental research) is not only possible; indeed, it has produced talented progeny who have immeasurably advanced our understanding of human functioning across the life span by further illuminating the mysteries of infant experience.