The present mixed study seeks to characterize how future natural sciences teachers perceive their didacticcurriculum performance and their promotion of scientific competence when implementing the subject Science for Citizenship in their pedagogical practice. The quantitative phase employs a non-experimental design, while the qualitative phase is a case study of fourth-year university students during the years 2022 and 2023. Performance perception is measured by a Likert scale and semi-structured interviews. Scientific competence is analyzed at levels (high, regular, and low) and discourse analysis is encrypted into codes and categories. The results indicate a regular perception to promote scientific competence. It also shows training deficiencies associated with: contextualization, curriculum interpretation, difficulties in science integration, and influence of the traditional teaching model. It is concluded that there are tensions in initial training when teaching Science for Citizenship due to the didactic-curriculum demands of this new subject.