Objectives The relational mode and engagement difficulties of individuals with borderline personality disorder (BPD) can elicit a variety of emotions in the clinician. Emotional activation and compassion fatigue are thus common and can lead to counterproductive interventions. Working with this clientele requires the ability to regulate negative emotions and inhibit associated behaviors. However, the processes involved in this emotional work are rarely made explicit and even less taught. The Project TANGO training was developed to help clinicians modify their emotional and behavioral reactions in the context of common complex interventions. Strategies from dialectical behavioral therapy are taught so that they can use them to self-regulate during emotionally demanding interventions. The purpose of this study is to evaluate the effects of this training on intervention skills and readiness. Method The Project TANGO training was evaluated using a mixed-methods design with 184 practitioners working with adolescents and adults in youth protection (YP) and CLSC settings. Measures of emotion regulation, attitudes towards people with BPD, quality of professional life and self-esteem as a worker with this clientele were taken before, after and 3 months after the training. Pre- and post-training focus groups were used to document the challenges of working with this clientele and to assess the more difficult to quantify effects. Results All of the pre-test measures showed more favourable scores for PJ workers than for CLSC clinicians. Qualitative analyses suggest that they use emotional regulation strategies, such as masking the true emotion and simulating another emotion, which have been associated with burnout. Among PJ workers, the effects of Project TANGO were significant for variables associated with readiness to intervene, suggesting more positive Perceptions and Attitudes towards the clientele (p=0.011, ηp2= 0.160 and p=0.036, ηp2= 0.120), more Compassion Satisfaction and a decrease in Compassion Weariness (p=0.001, ηp2= 0.222 and p=0.002, ηp2= 0.212) three months after the training. CLSC clinicians achieved benefits on their Perceptions (p<0.001, ηp2= 0.168), Attitudes towards BPD (p<0.001, ηp2= 0.185) and Satisfaction with Compassion (p=0.042, ηp2= 0.065) upon completion of the training. Conclusion This study shows that the two groups benefit differently from the training. The results suggest that the training resulted in a more accurate reading of the challenges of intervention among YP practitioners. On the other hand, since these dispositions were more present among CLSC clinicians before the training, they seem to have benefited from the training to increase their intervention skills.