Responsive Teaching is an early intervention curriculum designed to address the cognitive, language, and social emotional needs of young children with developmental problems. This innovative intervention model was derived from research conducted primarily with children with Down syndrome and their mothers. Results from these studies indicated that during the early childhood years, parents promote their children's development by engaging in highly responsive interactions throughout their daily routines. The effects of responsiveness are mediated by the impact it has on children's use of several pivotal developmental behaviours, such as social play, attention, initiation and persistence. Responsive Teaching helps parents learn to use Responsive Teaching strategies to promote the pivotal developmental behaviours that are relevant to their children's developmental needs. Research with 50 children with developmental problems and their parents indicated that Responsive Teaching was highly effective at addressing children's developmental and social emotional needs. The effects of this intervention were mediated by the impact that RT strategies had on children's pivotal developmental behaviours.