Increasing renovation costs and ever more limited public funding for urban regeneration in combination with a political desire to stimulate the development of a sense of ownership in urban regeneration neighbourhoods has brought about a growing interest in attracting private sector funding. Previous research shows that area-based urban regeneration generates immense private investments, primarily from local property owners, but also from external developers. For the latter, external private investments can enable large and strategic investments that contributes positively to the urban development. However, we believe that municipalities can become much better at attracting private investors and developers, partly because there is knowledge about the motives and backgrounds for the developers' engagement in the urban regeneration. Based on data from a number of case studies and interviews with developers we argue that developers own networks are more likely to lead them to the urban regeneration areas, than knowledge of the urban regeneration itself. Also, the study reveals a mutual knowledge-gap between the municipal planners and developers; planners have limited knowledge of developers' rationalities, and developers have limited knowledge of urban regeneration programs. Nevertheless, there is ample evidence that developers possess crucial competences in relation to the urban regeneration processes, for instance to establish a shared vision of a neighbourhood amongst different local actors involved, to negotiate with private as well as public parts, and - most importantly - to 'sell' the project to the right investors. Hence, there are several reasons for the public planners to increase the engagements with private developers in the urban regeneration. Compared to international research on private investments in the urban re-generation (Adair et al, 2007; Nappi-Choulet, 2006; Guy & Henneberry, 2004), we argue for more focus on the institutional context's role for attracting small-scale investors to the urban renewal. We propose that a lack of institutionalised information channels, boundary objects, inhibits increased cooperation between private sector investors and public planning authority. In the paper we suggest that particularly public planners need to change their views and practices in order to facilitate the levering of private investments, and that the concept of 'boundary objects' (Star & Griesemer, 1989) can be used as a way to bridge the knowledge-gap between public planners and private investor.