Developing persuasive and consistent models of educational performance has proved elusive. Existing modelling suggests no clear relationship between resources and student performance. This mirrors observed policy outcomes. A possible explanation is that the achievement process is a complicated interactive one such that simple linear additive formulations break down. This analysis presents a stylized model of achievement where unmeasured teacher quality interacts with both resources and specific educational programs. Standard econometric analyses then replicate the aggregate findings in the literature. A policy implication is that finding ‘best practices’ may fail without recognition of the fundamental interactions.