The sluggish supply response in most developing countries to the apparently favourable agricultural market situation of the past few years can be explained by the limited ability of price incentives to bring about an increase in production and marketed surplus in the presence of binding non-price constraints. This article characterises farm household heterogeneity in access to assets, markets and infrastructure drawing on household survey data from 15 developing countries. We relate this heterogeneity in access to household ability to engage successfully in agricultural output markets and find consistent supporting evidence for the hypothesis that this lack of access is significantly constraining their potential to engage successfully in agriculture.