An instance theory of attention and memory (ITAM) is presented that integrates formal theories of attention and memory phenomena by exploiting commonalities in their formal structure. The core idea in each theory is that performance depends on a choice process that can be modeled as a race between competing alternatives. Attention and categorization are viewed as different perspectives on the same race. Attention selects objects by categorizing them; objects are categorized by attending to them. ITAM incorporates each of its ancestors as a special case, so it inherits their successes.