This study examined regulatable quality and teacher-child interaction and, their influences on the quality of the attachment relationship developed by preschool children with their day care teachers. Observation and interview procedures were completed in 12 classrooms serving 194 preschoolers. Regulatable quality variables included teacher-child ratio, class size, and teacher qualifications. Teacher-child interaction was assessed with respect to rate, content (traditional, socially-oriented, or control/disciplinary style), and affective tone. Results indicated that class size and teacher-child ratio were especially variable, because classes were often combined for joint activities or were divided into small groups. Negative teacher affect occurred infrequently, but flat emotional tone was not uncommon. Controlling for child age, it was found that class size was negatively related to teacher-child ratio and teacher qualifications, and teacher-child ratio was positively related to teacher qualifications. The rate of teacher-child interaction was positively related to traditional and socially-oriented interactions. Control interactions were related to negative and neutral teacher affect, and negatively related to positive teacher affect. Class size was negatively related to interaction rate and traditional- and socially-oriented interactions. Teacher-child ratio was related to interaction rate and traditional interaction. Children's attachment security scores were negatively associated with neutral teacher affect and control interaction. The composite variables of quality and teacher-child interaction, formed from the results of a principle components analysis, were used in multiple regression analyses. Tentative support was found for paths between: (1) low quality teacher-child interaction and children's insecurity in the teacher-child relationship; and (2) regulatable quality and high quality teacher-child interaction. (Contains 21 references.) (KDFB)