Academic writing is one of the most important and complex competences to achieve in higher education, especially within highly specialized disciplines. A variable which has been related to writing performance and has shown to be an excellent predictor of students' academic success is self-efficacy. Despite its relevance, no instrument to assess self-efficacy in the production of academic texts in specific disciplines has been found. The objective of this work is to empirically develop and validate a Self-efficacy scale for disciplinary academic writing. The research, whose design is framed in the development of measurement instruments, had three central phases: a) definition of the construct to be measured, elaboration of items and validation of the pilot instrument; b) application of the instrument to a sample of 439 students from different programs at Chilean universities; and c) analysis of the construct's internal structure using the Exploratory Structural Equation Modeling (ESEM). As a main result, the Self-efficacy scale for disciplinary academic writing, consisting of 35 items, distributed in 5 dimensions, with adequate evidence of validity and reliability, was obtained. This instrument can be useful for those interested in the field of academic writing.