Insider threats represent a latent risk to all organizations, whether they are large companies or SMEs. Insiders, the individuals with privileged access to the assets of organizations, can compromise their proper functioning and cause serious consequences that can be direct—such as financial—or indirect—such as reputational. Insider incidents can have a negative impact on SMEs, as their resources are often limited, making it paramount to implement adequate cyber security measures. Despite its indisputable relevance, the empirical study of insider incidents from a criminological point of view has received little attention. This paper presents the results of an exploratory study that aims to understand the nature and extent of three type of insider incidents—malicious, negligent, and well-meaning—and how they are related to the adoption of cyber security measures. To that end, we administered a questionnaire among a panel of 496 Dutch SME entrepreneurs and managers and analyzed the results quantitatively and ...