Background: This preregistered study compares adolescents with mild-to-borderline intellectual disability (MBID) and typically developing (TD) adolescents on their susceptibility to peer influence. To understand why adolescents with MBID are susceptible to peer influence, links with inhibition, Theory of Mind (ToM) and negative interpretation bias are investigated. Method: We assessed 163 adolescents (111 MBID, 52 TD 14-19 years; 63% boys) using experimental tasks and self- and/or teacher-reports. Results: Adolescents with MBID and TD adolescents did not differ in their susceptibility to peer influence, inhibition, and negative interpretations. On two ToM instruments, adolescents with MBID performed weaker than TD adolescents. In a structural equation model, tested in the MBID group, inhibition, ToM and negative interpretation bias were not related to susceptibility to peer influence. Conclusions: This study revealed new insights by strong methods such as the multimethod approach, a full theoretical model testing relations between all constructs simultaneously, and the large sample.