This article refines and expands the debate on antecedents of company engagement in business partnerships for sustainability. It builds upon the Awareness–Motivation–Capability (AMC) framework and extends it by means of an in-depth qualitative study. The article thereby expands the understanding of antecedents of company engagement in business partnerships for sustainability. In particular, it advances on the elements related to company- and industry-level motivators and on microlevel aspects. Based on our research findings, we are able to extend the AMC framework's main categories and provide a more nuanced account of the underlying elements constituting them. To reach a more complete understanding of the antecedents of company engagement in business partnerships for sustainability, our analysis provides a general conceptual advancement while also investigating potential differences based on business size and industry.