Effectance, defined as the child's independent, effective interaction with people and things, is studied through observation of the play of 36 preschool low income black children. The children were observed and filmed in semi-structured play sessions, primarily with family dolls, doll furniture, and small baby bottle. Instruments used were: (1) the Play Session Behavior Scale, which includes 22 variables defining organization, involvement, and interpersonal responsiveness in play, and (2) the Psychosexual Content of Play Scale, which includes 13 variables defining the amount of content reflecting each of the five early psychosexual stages of development. It is concluded that: (a) Effective functioning as a learner at age 4 requires skills which became crystallized during the Anal Retentive stage, such as the ability to persist in tasks, take pleasure in accomplishments, and look for rules and order; and (b) Optimal functioning as a learner at age 4 is facilitated by skills arising out of the Phallic stage, such as curiosity, self-assertion, and an emerging sense of where one fits in the social order. Statistical tables and an appendix consisting of the instruments and rater's manual used comprise almost half of the document. (Author/NH)