In this paper we explore the nature of hybrid organisations and report on the existence over time in social housing in Ireland. We first review the literature to identify three different conceptualisations of the concept of hybridity and its relation to the study on nonprofit organisations. We then look at hybridity in social housing in Ireland over three centuries—drawing upon previous empirical research from Mullins et al. (Non-profit housing organisations in Ireland, North and South: changing forms and challenging futures. Northern Ireland Housing Executive, Belfast, 2003) and Rhodes (Public services as complex adaptive systems: a framework for theory development. Trinity College Dublin, Unpublished PhD Thesis, 2008)—to assess which of the conceptualisations is most relevant to the Irish context. We conclude that the ‘fit-for-purpose’ approach as represented by Dees and Anderson (Society 40:16–27, 2003) and explored in recent social entrepreneurship literature is most relevant to the Irish case, and suggest that this should be augmented by the argument put forth by Mullins et al. (Hous Stud 27(4):405–417, 2012) that the concept of hybridity is more analytically valuable as a dynamic process rather than a static description.

To complement contemporary nonprofit literature, which mainly offers theory-driven recommendations for measuring nonprofit effectiveness, performance, or related concepts; this article presents seven trade-offs for researchers and practitioners to consider before engaging in a nonprofit effectiveness measurement project. For each trade-off, we offer examples and suggestions to clarify the advantages and disadvantages of methodological choices that take various contextual elements into account. In particular, we address the differences between formative and reflective approaches, as well as the differences between unit of interest, unit of data collection, and unit of analysis. These topics require more in-depth attention in the nonprofit effectiveness literature to avoid misinterpretations and measurement biases. Finally, this article concludes with five avenues for further research to help address key challenges that remain in this research area.

In this article, I apply the contributions of Luhmannian systems theory to the analysis of the third sector, accepting, in realistic terms, the diagnosis of current societies as increasingly complex and the descriptions of third sector as hybrid. After identifying some of the main analytical elements and concepts, I propose applying it in two ways. First, with the illustration of organizations’ self-descriptions, I show how third sector organizations may be analyzed in light of the concepts of self-reference, reflexivity, and reflection to evidence both their operational closure and their structural couplings with other systems. Second, I refer to the self-descriptions of “sector” in terms of its self-reflection and semantics as different from other sectors and show that it is a paradoxical heterogeneous unity. I conclude by arguing for the usefulness of this analytical framework to understand contextually the meaning of the third sector in functionally differentiated societies.