To examine the interaction between biological and behavioral transmission of psychiatric disorders, comparisons will be made among groups of young children in families where a mother has a primary diagnosis of major affective disorder, bipolar disorder, obsessive-compulsive disorder, or no mental illness. The proposed study will determine (1) if the young offspring of affective, bipolar, obsessive compulsive, and no-illness mothers differ in behavior, (2) if mothers with affective, bipolar, or obsessive compulsive disorders behave differently toward their children than mothers without these disorders; (3) if these maternal differences can be related to differences in offspring behavior; (4) if maternal characteristics such as diagnosis, severity of disorder, symptom dimensions, or demographics are differentially predictive of child behavior; (5) if transmission across generations is specific in nature, i.e. if similar symptoms are apparent in parent and offspring; and (6) if the course of parent illness during the child's early years impacts on adaptive development. To test these hypotheses groups of 1. 2-1/2, and 4 Year old children who have mothers with affective, bipolar, and obsessive compulsive disorder, as well as those with no mental illness will be examined at home and in laboratory situations. Short-term convergent longitudinal studies will be completed from I to 2-1/2 years and from 2-1/2 to 4 years of age. At 2-1/2 years, 180 children and their families will be tested: offspring of a mother with major affective disorder (n-50), bipolar disorder (n-30), obsessive compulsive disorder (n-50), and no psychiatric disturbance (n-50). Of these, 120 of the 2-1/2 year old will have been seen at 1 year of age, and 120 will be seen again at the age of 4. Each parent will be given a structured psychiatric interview to determine DSM-III-R diagnosis as well as the degree of symptom expression. Children will be examined alone and in interaction with their parents for emotional responses and competence in cognitive and mastery tasks. Family interaction patterns will be examined as will home environments, social supports, and life stresses.