In which I visit the Big Apple and go large in the shade of that big Tree of Knowledge.

Everyone here in the basement believes in evidence based practice. Outside, most people in children's services do not.

How long before there are designers in Scandinavia, elsewhere in Europe and in the South producing something so radically different for children that America comes running?

Del Elliott talks standards of evidence, programme fidelity and scaling up, over an all American breakfast.

Despite getting hot and bothered over poor concept, unreliable measurement and spelling mistakes, Ernest can't help but be excited by some very powerful data.

Reasons to make the long-haul journey to the Blueprints conference.

Reporting from the Blueprints Conference in Denver, Michael Little observes how talk about 'real' families can influence the arguments for and against evidence-based practice.

Clarity, fidelity, rigor – and the lives of real people: getting to grips with the everyday reality of turning a blueprint into a working model.

Dr Jay Giedd of the US National Institute of Mental Health demonstrates how the study of brain development in adolescence is becoming mainstream – and the lessons emerging are all about changeableness and complex interactions between growing intellect and maturing emotions.

Is there a paradox creeping out of the research woodwork? The more prevention science learns from the findings of randomized controlled trials, the more it recognizes the importance of contextual factors hardest to measure, such as the influence of culture and social structure and how they interact.