This study investigates the relationship between infrastructure investment and economic growth at the aggregate and sectoral levels, namely, the industrial, agriculture, and services sectors for Pakistan over the period from 1972 to 2015. In contrast to earlier literature, we make a comparative analysis of the different composition of infrastructure investments, including public versus private investment and infrastructure investment in sub-sectors such as in power, roads, and telecommunication sectors. The long-run relationship is estimated using fully modified ordinary least squares (FMOLS) to address the problem of reverse causality. The main conclusion of this study is that both public and private infrastructure investments have positive but different effects on economic growth. In other words, the marginal productivities of private and public infrastructure investments differ across the different sectors of the economy. In most of the cases, public infrastructure investment has a larger impact on economic growth than private infrastructure investment. Two important policy implications emerge from this study, as follows: (1) The different elasticity estimates can be used by policy makers to quantify the impact of policies targeted at the specific sector and (2) the government should develop an enabled policy environment to attract private investment, with the consideration of structural characteristics of the various sectors. The involvement of the private sector in the provision of infrastructure would help to control the tight budgetary situation.