This chapter considers the clash between Alexander of Aphrodisias’ version of hylomorphism and the Stoic theory of pneuma-matter blending. For the Stoics, animals, plants, and inanimate natural bodies are composed of pneuma (‘breath’) and matter, and by blending with matter pneuma causes the composite to be what it is. Alexander argues that the Stoic theory is explanatorily inadequate, because pneuma cannot do the causal work needed, and Stoic blending cannot yield a unified whole. I examine Alexander’s objections, and I develop an account of how he means to avoid similar deficiencies in his own hylomorphic theory. While the Stoics face significant explanatory problems, Alexander’s view, it turns out, is not without difficulties. For the explanatory role given to the underlying bodies and their manner of combination (‘the upwards story’) leaves Alexander without a precise account of how and why the material basis is connected to the form of the composite.