The relationship between biodiversity and each ecosystem service or bundle of ecosystem services (e.g. win−win, win−lose or win−neutral) is an active field of research that requires structured and consistent information. The application of that research for conservation and decision-making can be hampered by the ambiguity found in the definition of the nursery function under the ecosystem service perspective. In this paper, we review how the role of nursery habitats is included in the ecosystem services literature, covering conceptual, biophysical and economic reflections. The role of ecosystems as nurseries is mostly analyzed in coastal environments. The main observation is that there is no consensus on the consideration of the nursery function as a service (e.g. which species or habitats) or on how to assess it (e.g. which indicators or valuation methods). After that review, we analyze three different interpretations given to the nursery function, namely the ecological, conservationist and economic point of view; and we distinguish between different types of assessment that may consider the nursery function. We conclude that the nursery function can be considered an ecosystem service on its own right when it is linked to a concrete human benefit and not when it is represented with indicators of general biodiversity or ecosystem condition. Thus, the analysis of the delivery of ecosystem services should be differentiated from the analysis of ecological integrity. Only with this distinction science may be able to quantify the link between biodiversity and ecosystem services and policy may be effective in halting biodiversity loss. Similar considerations could apply for other biodiversity constituents that may be treated as ecosystem services.