Errors in clinical decision-making are disturbingly common. Here, we show that structured information–sharing networks among clinicians significantly reduce diagnostic errors, and improve treatment recommendations, as compared to groups of individual clinicians engaged in independent reflection. Our findings show that these improvements are not a result of simple regression to the group mean. Instead, we find that within structured information–sharing networks, the worst clinicians improved significantly while the best clinicians did not decrease in quality. These findings offer implications for the use of social network technologies to reduce diagnostic errors and improve treatment recommendations among clinicians.