The Barnahus model was launched in Iceland in 1998, and it subsequently spread to all the Nordic countries. It is an interagency, co-located model for working with cases of violence and abuse against children that addresses two vital concerns of welfare societies: to process cases through the legal system and to offer support and treatment to victims. The model is currently recommended as a best-practice model on the European leveland understood as representing a radical change in the organisational setup related to such cases. This paper analyses the diffusion and implementation of the model in two different contexts: the Nordic region and the wider European arena, where the model is currently promoted as an important innovation. Drawing on the concept of social innovation, we explore the structural and contextual conditions for the diffusion of the model and discuss its role in the ongoing transformation of welfare societies' response to children exposed to violence and abuse. We identify the policy-making means by which the model is promoted today and conclude that it can lead to manifold institutional changes, both radical and incremental, and both desired and undesired, depending on how the original idea is translated and adapted in different contexts.