This article proposes to bring the sustainable product-service innovation (PSI) field into a next phase—after two phases of exploring why and how firms achieve sustainable PSI growth, we suggest to further focus on finding when they actually do so. Based on prior studies, we pinpoint and describe two main shortcomings in the current body of PSI literature: (1) an overemphasis on the firm level, and (2) an overuse of descriptive case studies. These shortcomings are used as stepping-stones for formulating a research approach that integrates Multiple Levels (namely, the firm, its environment, and its people), mixes different Methods (both qualitative and quantitative) and that turns researchers to Action (through advice and training). This MLMA approach offers ample new research opportunities and turns the servitization research community into a servitized community by leveraging academic insights to better support firms in improving their economic and environmental performance.