Integration in mixed methods involves bringing together quantitative and qualitative approaches. There is a need for practical examples of how to integrate the two approaches in an explanatory sequential design at the methods level and at the interpretation and reporting level. This article reports an explanatory sequential mixed methods study of adolescents' quantitative judgments about belief-related scientific arguments and qualitative reasons behind those judgements via interviews. This context is used to illustrate how integration can be achieved in an explanatory sequential design at the "methods" level, through the sampling frame and through the development of the interview protocol with a methodological joint display, and at the "interpretation and reporting" level through narrative and the use of a results joint display.