The number of people with dementia is growing rapidly due to population ageing. Several policy documents emphasize the importance of inter-organizational collaboration to deal with this increasing demand for care. Despite this aim, policy documents and interviews conclude that structural collaboration is difficult. This study answers the following research question: ‘How do experiences with collaboration in practice relate to principles in dementia policy documents?’ This question was answered in 39 interviews with national, regional and executive parties in the Netherlands and a policy analysis of the principles in the four most important dementia policy documents. Results show that despite the emphasis in policy documents on more collaboration, this is often not achieved in practice due to the lack of a clear governance structure and direction, due to the financing of individual organizations instead of collective activities and because cooperation between formal care parties and informal care providers is difficult. Furthermore, policy contrasts with practice in assumptions about the degree of independence of people with dementia, in assumptions about the interests of various parties and in a medical or social perspective on caring for people with dementia. This study concludes with recommendations to bridge the gap between policy and practice and to stimulate inter-organizational collaboration.