The Caregiver-Teacher Report Form (C-TRF) is an instrument frequently used by researchers and clinicians to assess psychopathology in preschool children based on information from early childhood education and care professionals. However, the measurement invariance of this instrument has not been investigated. Thus, the aim of the current study was to investigate the measurement invariance of the C-TRF for (1) girls vs. boys, and (2) for children below the age of three years old vs. three years or older, as measurement invariance is a prerequisite for a meaningful comparison of latent means between groups. Based on reports of 2904 children from 353 early childhood education and care professionals, our results showed full scalar invariance for an adapted C-TRF model, which supports the applicability of the instrument. However, awareness of the factor Somatic complaints and items with out-of-range parameters is warranted.