While infrastructure investments in developing regions may bring about aggregate benefits, the distribution of those benefits cannot be ignored. The present paper examines such distributional effects based on two illustrations: rural roads in Ethiopia and flood control systems in Bangladesh. In both cases, the infrastructures promote particular development patterns towards market-economic transformations and integration. We liken the introduction of these infrastructures to the addition of a catalyst in a chemical reaction. Rural roads, for example, catalyse existing flows of agricultural labour, while flood control catalyses agricultural productivity. Taking the analogy a step further, the effects of a catalyst are known to vary due to the presence of so-called inhibitors and promoters. Applying this to the two cases, the paper reveals that, among other factors, the ownership (or lack thereof) of modes of transportation in Ethiopia and land resources in Bangladesh represent significant promoters (or inhibitors) that can help to explain the unequal distribution of benefits. This question is by no means new; past technical assistance programmes were already fiercely criticized for exacerbating inequalities. Today, commercial and political interests are again intensifying infrastructural investments in developing regions with profound impacts on local economies and livelihoods. Revisiting the question of distribution is, therefore, as relevant as ever.