Introduction: This paper reports on a study undertaken for the UK Joint Information Systems Committee (JISC), which explored the economic implications of alternative scholarly publishing models. Rather than simply summarising the study's findings, this paper focuses on the approach and presents a step-by-step account of the research process, highlighting the combination of process mapping, activity costing and macro modelling. Method: The analysis relies primarily on existing sources, collating activity cost information from the wide-ranging literature on scholarly communication. Where necessary, these sources were supplemented by targeted informal consultation with experts. Analysis: We examine the costs and potential benefits of the major alternative models for scholarly publishing, including subscription publishing, open access publishing and self-archiving. Adopting a formal approach to modelling the scholarly communication process and identifying activity costs, this paper presents activity and system-wide costs for each of the alternative publishing models. It then explores the potential impacts of enhanced access on returns to R&D. Results: We find that different scholarly publishing models could make a material difference to the costs faced by various parties and to the returns on investment in R&D that might be realised. Conclusion: It seems likely that more open access could have substantial benefits in the longer term. While the benefits may be lower during a transitional period they would be likely to be positive for both open access publishing and self-archiving alternatives. (Contains 1 note, 1 table, and 6 figures.)