This article, which reposes on observations and experiences accumulated over around fifteen years and a number of empirical research projects, analyzes the impact of the researcher’s credibility and the relationship of trust in a qualitative research process. It is part of a process of self-reflection and introspection that draws out the importance of complex involvement and the essential role ethics plays in the qualitative investigatory process, while at the same time enhancing understanding of the link between the two. This article fits more broadly into the category of epistemological, methodological and ethical reflections on qualitative research. These concerns are at the same time constant, evolving and eternally renewed. It is structured around two main themes. On the one hand, it deals with a set of questions touching on credibility, trust, ethics and complex involvement, while at the same time it indicates the analytical perspectives that stem from these considerations. On the other hand, the data analysis is used in the article to show not only the relationship between complex involvement, credibility and trust, but also the dynamics of mutual reinforcement between ethics and complex involvement.