Variance-based sensitivity analysis can provide a comprehensive understanding of the input factors that drive model behavior, complementing more traditional system dynamics methods with quantitative metrics. This paper presents the methodology of a variance-based sensitivity analysis of the Biomass Scenario Learning Model, a published STELLA model of interactions among investment, production, and learning in an emerging competitive industry. We document the methodology requirements, interpretations, and constraints, and compute estimated sensitivity indices and their uncertainties. We show that application of variance-based sensitivity analysis to the model allows us to test for non-additivity, identify influential and interactive variables, and confirm model formulation. To enable use of this type of sensitivity analysis in other system dynamics models, we provide this study's R code, annotated to facilitate adaptation to other studies. A related paper describes application of these techniques to the much larger Biomass Scenario Model. has twenty five years of experience with infrastructure, energy, and transportation modeling, simulation, and analysis.Daniel Inman, a PhD soil scientist, has over ten years of experience in bioenergy feedstocks, modeling, and advanced statistics.Steve Peterson is an independent consultant and a Senior Lecturer at the Thayer School of Engineering at Dartmouth College. Steve has been involved in the teaching and application of dynamic modeling approaches since the early 1980s.Additional supporting information may be found online in the Supporting Information section at the end of the article.Appendix S1 Model documentation and annotated R code. P. Jadun et al.: Variance-based Sensitivity Analysis of the Biomass Scenario Learning Model 335