Practitioners and analysts widely consider distribution to be a critical element in marketing management. A customer can access a specific product only if it is available at a retailer. Apart from acting as a gatekeeper between a manufacturer and end-users, distribution and in-store availability significantly affect consumers’ choice decisions, manufacturers’ market share outcomes, and retailers’ assortment decisions. To better understand the role of distribution and in-store availability from both demand and supply perspectives, the objective of this thesis is to address three research questions: How, given consumer preferences and shopping patterns across multiple stores and different levels of in-store product assortments, does the realised availability of products to consumers affect manufacturers’ market share outcomes? What is the dynamic relationship between distribution coverage and market share for FMCGs (fast-moving consumer goods) at the SKU (stock keeping unit) level? How does the branded variants strategy used by a FMCG manufacturer affect retailers’ stocking decisions and the corresponding distribution coverage in the market and the typical depth of assortment a retailer stocks for a given brand? This thesis uses different methods in addressing three research questions with a dataset from Information Resources Inc. (IRI). The first essay combines a macro model of multibrand choice with a realised heterogeneous store choice-based availability model. The second essay examines an empirical generalisation with a structural vector autoregression model to capture the effects on distribution and market share of both baseline assortments and historical market performance. The third essay uses a game theoretic model to reveal the optimal degree for a branded variants strategy and then empirically tests a moderated mediation model. This work contributes to existing knowledge by improving the choice model approach used to understand the relationship between distribution and market share with a refined measure of distribution to account for purchase occasion-specific availability across different retailers; by generalising the shapes of the longitudinal effect of distribution on market share at the SKU level across several contexts; and finally by demonstrating the optimal degree for a branded variants strategy in a retail duopoly scenario and empirically testing retailers’ stocking and assortment responses to this strategy.