From 2011 to 2015, the U.S. intelligence community sponsored a series of forecasting tournaments that challenged university-based researchers to invent measurably better methods of forecasting political events. Our group, the Good Judgment Project, won these tournaments by balancing the collaboration and competition of members across disciplines. At the outset, psychologists were ahead of economists in identifying individual differences in forecasting skill and developing methods of debiasing forecasts, whereas economists were ahead of psychologists in designing simple market mechanisms that distilled predictive signals from noisy individual-level data. Working closely with statisticians, psychologists eventually beat the markets by producing better probability estimates that funneled top forecasters into elite teams and aggregated their judgments using a log-odds formula tuned to the diversity of the forecasters. Our research group performed best when team members strove to get as much as possible from their home disciplines, but acknowledged their limitations and welcomed help from outsiders. (PsycINFO Database Record (c) 2019 APA, all rights reserved)