Online activity data-for example, from dating, housing search, or social networking websites-make it possible to study human behavior with unparalleled richness and granularity. However, researchers typically rely on statistical models that emphasize associations among variables rather than behavior of human actors. Harnessing the full informatory power of activity data requires models that capture decision-making processes and other features of human behavior. Our model aims to describe mate choice as it unfolds online. It allows for exploratory behavior and multiple decision stages, with the possibility of distinct evaluation rules at each stage. This framework is flexible and extendable, and it can be applied in other substantive domains where decision makers identify viable options from a larger set of possibilities.