Despite empirical evidence on the positive effects of training on workers’ wages and employability, a puzzlingly large number of workers have never participated in any training course during their career. Using data from a representative sample of the Dutch labour force, we distinguish between recent participants in training, temporary non-participants, and chronic non-participants to better understand the drivers of training participation. We find a hard core of 17% of the working population who never participated in any training course during their working life. Chronic non-participation is related to workers’ intrinsic motivation to learn, low levels of task complexity, and a missing human resource development (HRD) policy in the firm where the worker is employed. However, temporary non-participants do not differ from recent participants when it comes to their non-cognitive skills, task complexity, or firm HRD policy. Chronic non-participants appear to earn significantly less than those who recently participated in training, but we do not observe any wage difference between temporary non-participants and recent participants. The latter result suggests that studies that do not distinguish between temporary and chronic non-participants in training underestimate the wage effects of training.