Considering the complex nature of vaccine hesitancy and the vast amount of misinformation surrounding vaccination, training healthcare professionals (HCPs) in vaccine communication is important to ensure high vaccine uptake. Recently, a new vaccine communication approach, known as the Empathetic Refutational Interview (ERI), was developed to help HCPs in conversations with patients who have vaccine concerns. In the present study, we developed and validated the ERI Skills Inventory (ERISI) for assessing learning outcomes of training in ERI. The ERISI measures are (1) ERI-related knowledge, (2) ERI-related skills, and (3) confidence in using the ERI. A sample of 103 HCPs who took part in ERI training responded to the ERISI, as well as questions about their self-efficacy in vaccine consultations and preparedness to refute arguments against vaccination, before and after the training. At two follow-ups, they also reported their understanding and use of the ERI. Results showed that the ERISI is sensitive to positive changes in ERI knowledge and confidence as a result of training. Participants also showed increased use post-training of ERI skills to demonstrate empathy toward patients. However, no change was observed for ERI skills that refute misconceptions and inform patients using factual information, which participants tended to already use at pretest. ERI knowledge correlated positively with ERI skills at posttest. ERI confidence demonstrated both concurrent and predictive validity. The ERISI questionnaire is a valuable tool for assessing ERI training outcomes that can guide training development to ensure learning and future skill application.