This paper studies the role of vouchers and caseworkers in training programs for the unemployed. We explore the unique features of the Hartz reform in Germany which simultaneously introduced training vouchers and imposed more selective criteria on participants. This allows us to go beyond the standard approach when we estimate the treatment effects for the most important type of training. Next to assessing the overall impact of the reform on the training’s effectiveness, we isolate the impact induced by changes in the composition of program participants (selection effect) from the impact based on the introduction of vouchers and related institutional changes (institutional effect). Our results show a small positive overall impact of the reform. The decomposition suggests that the selection effect is, if at all, slightly negative, and that the introduction of the voucher and related institutional changes increased both employment and earnings of participants. It furthermore appears that our findings are driven by skilled participants.