Capital accumulation, productivity growth and sectoral reallocation are salient features of economic development. These features are interconnected through the means for production and heterogeneous uses of different capital types across sectors, i.e. the investment network. Our paper introduces the first harmonized measures of the investment network across the development spectrum and documents novel empirical regularities, including systematic changes in the network with development. We propose a simple theory linking these disparities, which are endogenous to the path of sectoral prices, to differences in income per capita across countries. We show that the elasticity of output to sectoral productivity depends on the investment network, is highest in the Construction sector in developing countries, and in the ICT and Service sector in developed countries. Forces related to structural change, sectoral productivity and shifts in sectoral linkages drive this heterogeneity. For our sample of 58 countries, we show that 28% of cross-country differences in income per capita can be accounted for by disparities in the investment network. These differences are twice as large as the role of capital in income disparities obtained from standard development accounting.