COVID-19-related school closures have caused educational disadvantages for school children around the world. Against this background, many countries have introduced catch-up programmes to counteract the growing educational inequality. The Austrian summer school was offered as such a supportive measure and primarily targeted learners with learning gaps, lower language skills, and German as an additional or second language (L2). In addition, pre-service teachers (PSTs) were, and still are, mainly involved in teaching during summer school. This study examines the extent to which PSTs believe they have the requisite knowledge and skills concerning linguistically and culturally responsive approaches to teach in multilingual classrooms to support students in catching up with potential learning losses. For this purpose, an online survey study was conducted during the nationwide implementation of the Austrian summer school 2021. Altogether, 109 PSTs in Western and Northeastern Austria were surveyed before and after participating in the summer school. The results show that despite their lack of knowledge and skills around linguistically responsive teaching approaches, PSTs experienced the summer school as a positive learning opportunity that improved their understanding of multilingualism and, according to their own assessments, supported their teaching skills in linguistically and culturally diverse contexts.