We review the development of the Jamaican home visiting intervention for children under 4 years and its evidence base. The intervention has focused on supporting mothers to promote the development of their children through interacting in a responsive way, labelling the environment and activities. The curriculum is structured and cognitively orientated. It has been used in 13 studies in 4 countries, 7 in Jamaica, 6 in Bangladesh, one each in Colombia and Peru. In all studies some benefit to children's cognitive and language development has been found. Different types of children from severely malnourished to children living in poverty have benefited. Three long term follow ups have found sustained benefits to cognition; the longest study went to 22 years and found comprehensive benefits, to behaviour, school attainment and achievement, IQ, depression and wages. The curriculum is currently being used in 8 different countries and different delivery strategies are being evaluated including mother and child groups with meetings of different frequencies. A web package, Reach Up, to facilitate training with manuals and demonstration videos has been developed. Some unanswered questions include, what is the most effective age and duration for the intervention to have sustained benefits? Research is needed to find cost-effective implementation models and how to monitor and maintain intervention quality when going to scale.