Constructivist approach in teaching emphasises on development and acquisition of concepts among the learners by active construction and meaning making process. This new reform in education demands teachers to detach from traditional practice of knowledge transmission to constructivist teaching where the learners are guided to construct knowledge. This study aims to investigate secondary school teachers’ attitude towards constructivist approach in teaching in Gyalshing District of Sikkim. The study has followed convergent parallel design under mixed method approach. A total of 120 secondary school teachers who taught at the secondary level were taken as the sample for the quantitative phase of study while for the qualitative phase 15 teachers were selected from the sample. The quantitative phase of the study was carried out by a descriptive survey method through TASCAT scale. Data for the qualitative phase was collected through a semi structured interview prepared by the researcher. The findings of the study revealed that most of the teachers have favourable attitude towards constructivist approach on teaching. While with deeper analysis on interview findings it could be revealed the teachers understood the general principles of constructivism, but they could not fully grasp its core essence or how to effectively integrate these practices into their teaching. Additionally, several aspects, such as school culture, classroom culture, the structure of the curriculum, and assessment methods were found to have an impact on how teachers put their views into practice in the classroom.