Technology acceptance model (TAM) is one of the models that is used to explain the acceptance and use of technology with user perceptions and attitudes. Some researchers argued that TAM should include external variables, such as subjective norms, to improve our understanding of the effect of social impact on technology acceptance. The purpose of this study was to investigate the effect of subjective norms on preservice and in-service teachers' perceptions, attitudes and behavioural intention to use technology in Turkey. We adopted a multigroup confirmatory factor analysis method to establish measurement invariance across the groups and to investigate the relationships in the research model. The sample consisted of 324 preservice and 517 in-service teachers. Results revealed that attitude towards computer use was the most dominant predictor of behavioural intention in both preservice and in-service teachers. Subjective norms had a large total effect on behavioural intention in preservice teachers; however, the same effect was smaller in in-service teachers. Moreover, subjective norms played an important role in forming an attitude towards technology use in preservice teachers. On the other hand, in-service teachers considered the usefulness of technology in forming a positive attitude. We discussed the implications of the findings for both theory and practice.