The purpose of this study was to assess three methods of delivering in-service professional development regarding constructivist curriculum for early childhood educators. Educators in 44 not-for-profit child care centres in three Canadian cities were studied; 94 educators with formal preservice training participated. The three methods were (a) a consultant model, (b) workshops, and (c) a readings group. Global classroom quality was assessed with the Early Childhood Environment Rating Scale-Revised ([ECERS-R], Harms, Clifford, & Cryer, 2005), educators were interviewed about their beliefs regarding curriculum, and modified running record observations of educator-child interactions (i.e., guidance, directives) were assessed before and after the 15-week intervention. Over time the consultant model was associated with an increase in guidance interaction (i.e., promoting children's learning and development). A number of findings related to site were evident for quality of child care and educator beliefs, and highlight the challenges associated with conducting multi-site research studies. Implications for providing in-service professional development regarding curriculum are discussed.