We have presented an analysis of findings from a ten-year observational study of infants in their second year of life, with a focus on boys. Tracing the sexual development and its relation to development in the object relations and cognitive spheres, we found similarities between boys and girls and sharp differences as well. These latter become evident shortly after the discovery of the anatomical difference. We believe that the differences in reaction to this momentous event account for the greater trouble the girl has in the rapprochement crisis. Our direct observational studies of infants served to clarify many of the preoedipal dynamic currents which in turn affect the form of the oedipal constellation. We have established some sets of conditions which are likely to lead to a negative or positive form of oedipal

attachment, and have described the typical and some of the atypical patterns of preoedipal development in both sexes.