This article considers infant and toddler boys' unique susceptibilities to caregiving inadequacies that might lead to trauma in their development. It does so by examining the results of research, which point to three areas where boys are likely to have particular difficulties--their slower developmental timetable, their different relationship with their mothers, and their tendency to externalize frustration and stress. The authors provide background to help home visitors and others who engage with caregivers around the problems of boys in infancy, childhood, and adolescence. They suggest that boys, especially when raised under trauma-inducing conditions in early childhood, often develop in ways that are different than girls raised under similarly inadequate circumstances. These early childhood influences persist into later life and may be seen in school failure, conduct disorders, and other boy-predominant psychopathologies.