INTRODUCTION: Interactive workshops are often the default mechanism for sharing knowledge across professional and sector boundaries; yet we understand little about if, and how, they work. Between 2009 and 2011, the Research to Reality programme in North East England ran eight stand-alone facilitated multi-agency workshops focused on priority public health issues. Local authorities, the health service, and academe collaborated on the programme to share latest evidence and best practice METHODS: A realist evaluation asked the overarching question 'what worked where, for whom, and under what conditions' regarding the knowledge exchange (KE) mechanisms underpinning any changes. Data were collected from fifty-one interviews, six observations, and analysis of programme documentation. RESULTS: 191 delegates attended (local authority 46%, NHS 24%, academia 22%, third sector 6%, other 2%). The programme theory was that awareness raising and critical discussion would facilitate ownership and evidence uptake. KE activity included: research digests, academic and senior practitioner presentations, and facilitated round-table discussions. Joint action planning was used to prompt informed follow-up action. Participants valued the digests, expert input, opportunities for discussion, networking and 'space to think'. However, within a few months, sustainability was lost. There was no evidence of direct changes to practice. Multiple barriers to research utilization emerged. DISCUSSION: The findings suggest that in pressured contexts exacerbated by structural reform providing evidence summaries, input from academic and practice experts, conversational spaces and personal action planning are necessary to create enthusiasm on the day, but are insufficient to prompt practice change in the medium term. The findings question makes assumptions about the instrumental, linear use of knowledge and of change focused on individuals as a driver for organizational change. Delegates' views of 'what would work' are shared. Mechanisms that would enhance interactive formats are discussed.