STEM education is established as an alternative for developing 21<sup>st</sup> century skills, with the premise of integrating its component disciplines. Although numerous studies exist on the subject, STEM teacher training programs are not widely discussed. Therefore, a systematic literature review was conducted in Scopus and Web of Science to identify the intentions of the training and the design and implementation of such teacher training programs. Among the 15 articles identified, there are three groups of intentions: Improving knowledge, developing competencies and skills, and changing attitudes and perceptions. Five methodological strategies were identified: project-based learning, problem-based learning, collaborative learning, ODR (observation/discussion/reflection) approach, and design-based learning. Disciplinary integration can be achieved through content or competencies. It is concluded that design-based learning is the most appropriate strategy for disciplinary integration. It is recommended that research be conducted to measure the impact of modality and time of training on the development of STEM competencies.