The use of ‘Darwinism’ and generalizations of Darwin's idea outside the domain of its traditional biological application are advancing. In the field of industrial marketing, this has appeared mostly in the form of an interest in using biological analogies or isolated parts of a fuller Darwinian theory when theorizing about business relationships. In this article, we combine the general advancements of Darwinism in social science with the recent Darwinian-inspired theorizing on business relationships. The article reviews business relationship studies within marketing that explicitly uses Darwinism and results in the identification of six gaps and directions for future research. The most significant implication of the review is that investigations into the evolution of business relationships should account not only for the mechanism of selection but also for the mechanisms of variation and retention, in order to take proper account of the Darwinian explanatory paradigm. By suggesting ‘generalized Darwinism’ as an overriding framework, we argue that it is time to go from merely flirting with some Darwinian ideas to explicitly exploring the promise of using the Darwinianexplanans in research on business relationships. We put forward suggestions on how central Darwinian mechanisms could be warranted and conceptualized in a theory explaining the evolution of business relationships.