The extent to which students identify with science, technology, engineering, and mathematics (i.e. STEM identity) is crucial in influencing them to pursue STEM-related careers after compulsory education. Given the predictive power of this construct, this study explores Thai students' STEM identities by focussing on three components (i.e. interest, performance, and recognition) in light of their gender, educational programme, and career aspiration. One hundred and thirty-one students in Grades 10-11 from two secondary schools participated in the study. A Likert-type questionnaire was employed to gather data, which were subsequently transformed into interval scores using Rasch analysis. Inferential statistics were used to analyse the data. This study reveals that male and female students do not significantly differ in terms of their interest in and recognition of STEM. However, gender differences manifest regarding performance in STEM. Those studying in STEM-focussed programmes are likely to show stronger STEM identities than those in non-STEM programmes. Despite this tendency within the STEM-focussed programmes, the students' recognition of STEM varies by school. Those with career aspirations towards STEM are likely to exhibit stronger STEM identities than those who aspire to non-STEM careers. Based on the data, this study suggests a hypothesis regarding learning progression for students' STEM identities.