<p>Critical minerals strategies increasingly emphasise the need to move beyond extraction and establish domestic or allied processing capacity. Yet the conditions required to attract processing investment remain poorly specified. This paper argues that processing is neither simply an extension of mining nor governed by an entirely separate set of determinants. Rather, it changes the relative weight, configuration and timing of familiar investment conditions. While mining investment is anchored in geological prospectivity, tenure security, fiscal stability, regulatory clarity, infrastructure and social licence, processing is more strongly shaped by feedstock security, energy costs, industrial infrastructure, technology capability, product qualification, offtake demand, market structure, waste governance and policy durability. The paper defines processing as midstream industrial conversion through smelting, refining, separation, purification, chemical conversion, active-material production and processing from secondary feedstocks. It develops a comparative diagnostic framework for assessing investment conditions in critical minerals processing and introduces the concept of strategic deliverability to explain the gap between policy ambition and bankable midstream projects. The framework differentiates processing routes through a typology and is applied diagnostically to project and country cases spanning rare earths, graphite, cobalt, nickel, bauxite and lithium. It argues that processing investment is attracted not by mineral endowment alone, but by coherent industrial ecosystems capable of reducing commercial, technical, regulatory, social and geopolitical risk.</p>