The effects of small-scale interventions often prove much lower than expected when they are implemented at a large scale. We illustrate the problem and its potential causes using a number of examples from the early childhood intervention literature. We delve deeper by introducing a basic logical framework allowing us to discuss the key factors in assessing whether a program is ready to scale, particularly with regards to uncertainty in the potential outcomes of small-scale interventions. We conclude putting forward a set of concrete recommendations on how to bridge the science of using science and real-life policy.