Abstract We aimed to investigate (1) if trainee therapists differ from controls regarding childhood maltreatment and adult attachment and (2) if there are associations between childhood maltreatment, adult attachment and the alliance bond capacity. To answer the 1st question, a sample of 134 trainees and psychology students was matched to population-representative controls (CTQ: N?=?2504, ECR-S: N?=?2555) and compared on the Childhood Trauma Questionnaire (CTQ) and the Experiences in Close Relationships Scale (ECR-S). For the 2nd question, the Facilitative Interpersonal Skills task was used to measure trainees’ alliance bond capacity. Regression analysis was performed with age, gender, training status, CTQ and ECR-S scales as potential predictors. We found that psychology students and trainees reported more childhood emotional abuse (t?=??6.268; p?<?0.001), but less physical neglect (t?=?2.927; p?=?0.004), a lower tendency to minimize or deny adverse experiences (t?=?5.415; p?<?0.001) and less attachment avoidance (t?=?3.048, p?=?0.003) than controls. The alliance bond capacity was predicted by greater therapeutic experience (students vs. trainee, ??=??0.284, p?=?0.003; with vs. without licence to practise, ??=??0.218, p?=?0.025) and greater childhood physical abuse (? =?0.200, p?=?0.035). Our results emphasize addressing therapists' personal wounds. The potential beneficial effects, suggested by the positive association between physical abuse and alliance bond capacity, require further investigation and replication.