The concept of socioeconomic status (SES) has had a central and longstanding role in the social sciences. In addition to the study of class differences in social status per se, SES has served as a predictor, outcome, or control variable. Furthermore, it is often utilized to designate characteristics of samples being investigated. In developmental psychology, it has also served as a global index or appraisal of the environmental context in which children are reared. This chapter addresses the following issues: (l) nature of the relations among SES factors in a cohort of families studied longitudinally across an interval of almost two decades; (2) pervasiveness of SES to various domains of children's psychological functioning; and (3) relations between SES and children's family environment.