The influences of structural economic factors, social ecology, and culture in producing young absent fathers in the inner city and in defining relationships with their children are examined. Ethnographic data on three low income urban neighborhoods in Brooklyn (New York) are reported and compared with respect to the careers of young males, patterns of sexual activity and contraception, and responses to early pregnancy. The three neighborhoods varied in ethnic composition. One was predominantly White, and while not wealthy, had larger median income levels than the predominantly Black and Hispanic neighborhoods investigated. Data are reported for 48 young men. Comparisons of these young men demonstrate the interrelated influences of structural economic factors, culture, and social ecology in shaping the processes of family and household formation. The high rates of female-headed and aid-receiving households in the minority neighborhoods were related to the lack of wage-paying jobs for men and to social ecological factors. In all three communities, a young man was expected to at least try to support his children. Social policy that hopes to improve persistent poverty must move beyond the assumption that uncontrolled sexuality and an undeveloped work ethic are the root of the problem. Policies and programs must recognize the powerful structural economic factors that concentrate poverty and dependency in the inner cities; also, males must be defined as important parts of the solution and not merely as sources of the problem. Some innovative efforts in this direction have recently been undertaken and these efforts must be recognized as part of a comprehensive and intensive program of services. A list of nine references is appended. (SLD)