Like Anderson’s schema for developing rational models of cognition, a resource-rational model can be developed in four simple steps: 1. Function: Formalize the problem that the cognitive mechanism solves and charac- terize the optimal solution (computational level of analysis). 2. Model of mental computation: Posit a family of algorithms that approximate the optimal solution and their computational costs. This can be done by defining an abstract computational architecture by a set of elementary operations (e.g., to draw one sample from the posterior distribution) and their costs (e.g., based on execution time). 3. Optimal resource allocation: Find the algorithm in this class that optimally trades off approximation accuracy against time and other resources (e.g., by maximizing expected utility per unit time or the value of computation; see below). 4. Evaluate and refine: Compare the model’s predictions to human behavior. Revise the functional characterization (Step 1), or the model of mental computation (Step 2) and the resulting algorithm (Step 3) accordingly. Alternatively, one might pro- ceed to the next level below by modeling how the basic operations might be approximated or considering additional resource constraints.