This dissertation introduces and discusses Winnicott’s (1958/1974) capacity to be alone construct and how it is engendered in a child by an attuned environmental framework. Literature from the psychoanalytical, developmental, attachment, and trauma fields are utilized to operationalize the capacity to be alone in terms of attachment status, emotional regulation, executive functioning, and impulse control. The goal was to generate an object relational-developmental framework that will be used as a non-pathologizing lens by which to view the internalizing and externalizing behaviors of adolescents in foster care as well as of youth who have not been placed in substitute care. Clinical implications that result from this model are examined, as well as recommendations for future research.