Research shows that personal initiative training is a promising way to increase entrepreneurs’ personal initiative. However, it is not clear how post-training personal initiative develops over time and why some entrepreneurs hold up personal initiative, whereas others revert to their old business routines. In a field experiment with 805 small and medium-sized business owners, we investigate the influence of individuals’ need for cognition on the maintenance of entrepreneurs’ personal initiative after training. Entrepreneurs high in need for cognition show a reduced decline of personal initiative after training. Our findings contribute to the development of interventions which can have long-term effects on personal initiative behavior.