The outcome of Britain's referendum on EU membership came as a surprise to many. Most forecasters placed low probabilities on the "leave" campaign winning the day. Join the GJ community in taking a moment to reflect, learn, and share the lessons of Brexit. The post-mortem process is one of the key ways in which we become better forecasters (Superforecasting). As you compare your forecasts with the way events unfolded, what is most striking? What have you learned about forecasting? Was this a low probability event that just happened to occur or did most forecasters underestimate the odds of Brexit? What key risk factors were missed? What lessons can be drawn and which of those lessons can be applied more broadly to other forecasting questions? Are you changing your assessment of any other questions based on the lessons you have learned here? Please use the rationale box to post your reflections on the outcome of the Brexit referendum and the forecast box to indicate what you believe the true probability was for remain to prevail. This is an open question that will not be scored.