This document outlines steps for conducting a Lean UX workshop to define hypotheses. It discusses establishing assumptions about customers, desired outcomes, and features to test assumptions. Participants brainstorm potential users, needs, and metrics to measure success. Features are then organized into themes. Hypothesis statements are created linking assumptions about doing something for certain people to achieve outcomes, with evidence of success. The riskiest assumptions are prioritized for initial testing to reduce risk and waste. The goal is to define hypotheses to guide product development in testing assumptions.