Background: Face-to-face class suspensions during the coronavirus disease (COVID-19) pandemic in 2019 increased telepractice in speech and language therapy. However, little is known about speech and language therapists’ (SLTs) perceived effectiveness of telepractice and its antecedents.Aims: To examine the use of telepractice and the factors affecting its perceived effectiveness in Hong Kong mainstream schools during COVID-19.Methods & Procedures: Seventy-two school-based Hong Kong SLTs completed a 110-item online survey with six structural components: (1) concerns, (2) adoption, (3) student selection criteria, (4) perceived effectiveness, (5) continuous professional development and (6) attitudes/beliefs.Outcomes & Results: Over 90% of respondents adopted telepractice during the pandemic. Confirmatory factor analysis identified reliable constructs from their component measures. These participants reported great telepractice difficulties (especially in therapy preparation and managing students’ attention and/or communication). Mixed-response analysis revealed that psychosocial factors (i.e., students’ engagement and SLTs’ attitudes towards telepractice) but not professional practice skill factors (i.e., student client selection criteria and SLTs’ years of experience in school settings) contributed to SLTs’ self-perceived effectiveness of telepractice.Conclusions & Implications: Our findings suggest that psychosocial factors play a more important role than professional practice skill factors in the self-perceived effectiveness of telepractice. Copyright © 2022 Royal College of Speech and Language Therapists.