The probationer–probation officer working alliance plays an important role in the outcome of probation supervision. This study explored the development of the working alliance between probationers and probation officers in the Netherlands, from the perspective of both probationers and probation officers. More specifically, we explored the significance of different aspects of the working alliance at the start of probation supervision and after a three-month period, as well as the role played by critical incidents during the supervisory process and their subsequent effect on the working alliance. Overall, the study showed that clarity over goals and restrictions was initially the most salient issue for both parties, and that after a three-month period the working alliance evolved into a trusting relationship. Several incidents were identified, probationers identified more positive moments and less negative moments than their PO counterparts. If these types of incidents are managed accordingly by the probation officer, then they can ultimately serve to strengthen the relationship.