Defensive decision making occurs when a manager ranks an option as the best for the organization yet deliberately chooses a second-best option that protects him or herself against negative consequences. We study 950 managers in a public administration to analyze the frequency and causes of defensive decisions. We find that at each hierarchy level defensive decisions are widespread. On average, 2.5 out of the 10 most important decisions respondents made within the last 12 months were defensive. Overall, 80% of managers indicated that they made at least one defensive decision and 17% even stated that at least half of their decisions were defensive. We identify as a major cause a team’s approach to failure, that is, whether the reaction to failure is to seek someone to blame as opposed to identifying the underlying causes in order to learn how to prevent similar failures in the future. Given that managers are often confronted with an uncertain environment where a positive outcome cannot be ascertained, such an approach to failure can lead to a severe decline in the performance of the organization.