What determines the distribution of establishments in terms of size and life-cycle growth? How are those determinants related to aggregate productivity? We provide novel answers by developing a framework that uses price and quantity information on establishments outputs and inputs to jointly estimate the demand and production parameters, and subsequently, establishments quality-adjusted productivity, deriving both micro-level and aggregate implications. We find that the dominant source of variation in establishment size is variation in quality/product appeal but that variation in technical efficiency plays an important supporting role. Multiple factors dampen dispersion in establishment size including dispersion in input (quality-adjusted) prices, markups, and residual wedges. Relatively moderate dampening factors induce large aggregate allocative efficiency losses relative to their absence. We show that joint estimation of the parameters of the demand and production function crucially affects inferences on the determinants of the size distribution of firms and their implications for aggregate productivity.