Behavioral change in adolescents is often an important aim of residential youth care, but difficult to achieve. Care workers can increase the intrinsic motivation of adolescents to change their behavior by applying Motivational Interviewing (MI). The aim of this study is to investigate whether there is a difference in workers’ performance vis-à-vis adolescents before and after an MI training course. To measure this difference, we coded transcripts of audio recordings of one-on-one conversations between adolescents and workers, using the MITI 4.2.1 and MISC 2.5. We compared the transcripts made before the MI training course with the transcripts made after the training course. The results show that the 13 workers made significantly more use of MI adherent behaviors after the training course. Moreover, a trend toward using fewer MI non-adherent behaviors after the training was observed. The results suggest that workers are able to evoke more ‘change talk’ with adolescents after a training course. In conclusion, after attending a training course, workers are able to engage in conversations that are more in line with the MI-spirit. However, these are still not “real” MI conversations yet. We recommend to train workers more intensively in how to apply MI.