In the current search for tools that encourage and assess learning and development, personal development plans (pdps) are being used ever more frequently by organizations. A pdp is an assessment tool used by the employee to reflect on, to document the competencies s/he has been working on and to present his/her plans for further development. This study conducted among employees working in a governmental organization in the netherlands (n = 287) focused on the pdp practice as conceptualized by three supporting conditions: learning and reflection, information and feedback and the motivating supervisor. It examined which of these features enhance the undertaking of learning activities, expertise-growth, flexibility towards changing circumstances and performance. Results from the hierarchical regression analyses indicate that a motivating supervisor, information and feedback and reflection by the employee on the basis of his/her pdp affect whether or not a pdp contributes to the four measured output variables. Next, by conducting mediation analyses evidence is found for the mediating role of undertaking learning activities in the relation between the pdp practice and two output variables.