This book presents a multi-market framework of market and policy analysis that explicitly accounts for the empirically relevant heterogeneity in consumer preferences and producer characteristics. The explicit consideration of consumer and producer heterogeneity represents a significant departure from the representative consumer and producer that have been at the center of most of the literature on market and policy analysis, and enables the distributional impacts of changes in market conditions and policies to be fully identified. The framework is used to analyze the system-wide market and welfare impacts of a number of changes in market conditions (like changes in consumer preferences, costs and market structure) and policies (like subsidies and taxes) on one of the products in the system. Consistent with a priori expectations, the use of the framework unveils impacts masked by the conventional market and policy analysis.