Introduction : Traditionally, elderly care organizations play a pivotal role in integrating care for an ageing population, but recently this role has been challenged due to competition from other service providers, such as for-profit organizations, hospitals, home- and primary care organizations. In addition, the increasing complexity of current health care, combined with ageing and housing issues as well as rising co-morbidity in Belgium leads to a rising demand for collaboration. Not only do elderly care organizations have to deal with more and more tasks that are unique, but also are resources distributed across various service providers. As such, elderly care organizations are moving slowly from managing mainly physical assets such as housing facilities towards more intellectual and relational capacities and treatment services resulting into shared service centers and tailor-made health and social care solutions. Theory/methods : Although a number of factors have been proposed how to integrate health- and social care service delivery, collaboration pervades most discussions. We argue in this article that elderly care organizations follow a combination of three underlying strategic motives based on effectiveness, efficiency and legitimacy criteria to make a conscious, intentional decision to establish a relationship with other organizations for explicitly formulated purposes. We conceptualize these relationships as three ideal types: solitary, merger or collaboration and propose that the presence or absence of these types is explained by a combination of the changing nature in the task, the organizational configuration and its interdependency on others in the external environment. The article presents a case survey approach of 18 elderly care organizations. Data were collected in a five months period of time by using semi-structured interviews of key representatives and a survey. In addition, five workshops were organized and secondary data on elderly care organizations was collected. We applied Fuzzy-Set Qualitative Comparative analysis to analyze what, if any, combination of determinants explains whether elderly care organizations act solitary, merge or collaborate. Results, conclusion and discussion : Implications of the findings for elderly care organizations are discussed in light of the rising health care issues and increasing competition in Flanders Belgium. In particular, we are interested in which combinatory recipes, if any, of task, organizational configuration, and interdependency explain the presence or absence of a particular ideal type of collaboration. Furthermore, future recommendations are presented to further the development of how elderly care organizations can deal with their changing role in the healthcare system.