Marketing channels are among the most important elements of any value chain. This is because the bulk of a nation’s manufacturing output flows through them. The intermediaries (e.g., distributors, wholesalers, retailers) constituting marketing channels perform specific distribution functions, such as transportation, storage, sales, financing, and relationship building, better than most manufacturers. Over his distinguished career, Louis P. Bucklin investigated many questions about the structuring and functioning of marketing channels using conceptual, empirical, and microeconomics model-based methodologies. Today, the academic marketing literature contains hundreds of articles that have employed these three broad classes of methodologies to investigate issues of channel intermediaries’ inter-organizational relationships, for example, power-dependence, relational outcomes, conflict and negotiations, and manufacturing firms’ channel strategy, for example, channel structure, selection, coordination, and control. So far, however, there has been no review of how the three different methodologies have contributed to advancing knowledge across this set of channels research domains. This paper is the first that aims to (1) chart how channels research employing each of the three classes of methodologies – conceptual, empirical, microeconomics model-based – has evolved over seven decades along with current trends; (2) review the contributions and shortcomings of research to date using these methodologies; and (3) suggest future research opportunities using these methodologies, separately or in an integrated fashion.