Research has shown contradictory results on the relationship of infant attachment security to play and mastery behavior, at times predicting the cognitive quality of play and at other times predicting the affective quality of play. In order to test the hypotheses that, during play, attachment security would predict only positive affect, temperamental differences would predict negative affect, and maternal intelligence would predict the amount of symbolic representation, an investigation was conducted of 102 mother-toddler pairs from urban low-income families. Toddlers were 40% black and 60% male and were assessed with respect to free play and attachment security in visits at 12 months and again at 18 months. Additional evaluations were conducted of maternal teaching sensitivity at 12 months and the quality of the home environment at 15 months, while at 24 months mothers were tested to estimate their intelligence. Results of the study included the following: (1) toddlers with secure attachments showed more positive affect at 12 months, but there were no differences in positive affect observed at 18 months; (2) with respect to temperamental differences, low-reactive toddlers showed less negative affect during play and no differences in play level at 12 months only, while by 18 months they were playing less at low levels of non-symbolic play; and (3) the relation between maternal intelligence and symbolic representation depended on age and gender, with representation increasing with maternal intelligence for girls only. Six tables of findings are included. Contains 14 references. (AC)