This technical note describes the process of hypothesis-driven thinking, using examples from strategy consulting, medicine, and architecture. Associated with the scientific method, hypothesis-driven thinking focuses on the creative generation of alternative hypotheses and on their subsequent validation or refutation through the use of data. Hypothesis generation asks the creative question, "What if ...?" Hypothesis testing follows with "If ..., then ..." and brings relevant data to bear on the analysis. Taken together, and repeated over time, this sequence allows us to pose ever-improving hypotheses without forfeiting the ability to explore new ideas.