Evaluations of intervention programs seek to present high-quality design, measures and data to assess their merit and worth. While evaluations differ in their purpose, theoretical framework and methodology, their collective aim is to obtain relevant and meaningful information to inform practice, research, and policy. As such, evaluation findings serve to build a body of knowledge on effective approaches to promote designated psychological outcomes, critical to an individual's overall health and well-being. However, as examined in this e-book, methodological weaknesses directly limit the potential of evaluations of intervention programs. As discussed by Chacón-Moscoso and Sanduvete-Chaves, methodological weaknesses can be attributed to how to define and measure methodological quality and the contextual dependency of instruments designed to measure this quality. In response, this e-book provides a collection of studies on methodological approaches to promote the quality of psychological interventions. Specifically, 10 original works published in the Research Topic Methodological Quality of Interventions in Psychology are included. The papers are organized into two chapters. Concretely, Chapter 1 includes studies pertaining to methodological approaches to enhance the quality of psychological intervention, being context independent solutions. Furthermore, Chapter 2 presents original work in different areas (health, education, sport and social welfare) where methodological quality has been better assessed. Collectively, the papers in this e-book serve to expand the awareness of practitioners and researchers interested in psychological interventions of the critical role of methodological quality in this work. This research was funded by the projects 1150096 (Chilean National Fund of Scientific and Technological Development, FONDECYT); and PSI2015-71947-REDT (Spain’s Ministry of Economy and Competitiveness).