The aim of this study was to develop a Teacher and Classmate Support Scale-Taiwan Version (TCMS: TW) and test for its validation with a sample of 474 Taiwanese children and adolescents. This cross-cultural research replicates the two-factor structure of the original scale. We found evidence of good internal, composite, and test-retest reliability for the TCMS: TW. The Average Variance Extracted (AVE) was obtained for both the convergent and discriminant evidence of validity. Further evidence for convergent validity also came from the Pearson correlation coefficients (r) among the TCMS: TW, academic achievement, life satisfaction, and self-esteem. Our study found measurement invariance across gender groups. Results of the study revealed that the TCMS: TW is a psychometrically sound instrument measuring teacher and classmate support.