Purpose The motivations behind co-branding alliances, the differences in performance between the paired brands and the emergence of “spillover effects” have been pillars of the marketing research agenda for almost three decades. We observe an extensive number of studies on co-branding alliances, combined with multiple theoretical perspectives and empirical approaches informing extant literature. The purpose of this paper is to summarize of the state of the art of this research. Design/methodology/approach The authors offer a systematic literature review of 190 papers on co-branding alliances. The authors portray a picture of the theories informing co-branding research and build a conceptual framework that summarizes the concepts and variables used in this literature. Finally, 11 interviews with managers and consultants of European firms help to reveal potential problems in practice and needs that are not captured by previous studies. Findings The authors develop a map of theories used to investigate co-branding alliances and build a conceptual framework linking motivations, co-branding alliance implementation and outputs. Finally, the authors propose a structured research agenda. Research limitations/implications The main implication relies on the structured research agenda. Practical implications Practical implications include the identification of the variables and dimensions involved in a brand alliance to exploit the strengths and moderate the weaknesses of a brand. Originality/value This paper highlights how co-branding is embedded in different contexts and dimensions regarding both firms and consumers. The two maps presented in this study underscore the interdependence among such dimensions. The authors interview marketing experts to validate the conceptual framework and to help us extract the managerial implications that stem from it.