This contribution aimed to argue for and illustrate the benefits of implementing a triangulation strategy to develop mixed-methods design research in psychology. Based on the example of a French research that expounded on a qualitative approach to medical decision-making in oncology, it intended to suggest how a multiple triangulation strategy can be developed and implemented when seeking theoretical development. Therefore, it helped to offer a relevant case of how triangulation processes can be concretely put into action. Guiding the qualitative development of two studies and multiple analytical steps, the triangulation strategy appeared to be useful for shedding light on different aspects of the phenomena (triangulation of the data collection methods). It also appeared effective because it provided data corroboration (triangulation of the data analysis methods), informed the plausibility of the analytical ideas developed through each operation (triangulations of the data analysis methods, of the researchers), and progressively refined comprehension of the phenomena. Because this triangulated research strategy was developed based on an explicit epistemological and theoretical framework, it encouraged the combination of qualitative and quantitative analyses in a consistent setting which fostered the use of the added value of each of them. This strategy, which relied on substantial researcher involvement, in turn, fostered theoretical analyses contributing to non-medical influences both in the field of medical decision-making and the Social Representations Theory. Elucidating perceived psychological and relational patients’ characteristics involved in medical decision-making , this research contributed to the literature in this field of research which is more centered on sociodemographic attributes (Clark, Potter & McKinlay, 1991; Hajjaj et al., 2010). Moreover, although the studies developed in this field have informed those characteristics’ effects on therapeutic proposals, the triangulation strategy developed through the association of these observations with semi-structured interviews went further by revealing the different logics underpinning their use by physicians. The perceived patients’ non-medical characteristics, combined with patients’ clinical characteristics, helped physicians to form a quick idea about the person they were encountering. These characteristics were also used as predictors of patients’ ability to bear the treatment, therapeutic observance, and treatment preferences. These results, emphasizing the functions of patients’ perceived characteristics in medical decision-making, complement and broaden theoretical interpretations focused on discrimination and/or stereotypes, which are often used in psychology to explain the effects of the characteristics on treatment proposals (Lutfey et al., 2008). In our research, and, especially, in the fifth analytical step, the patients’ non-medical characteristics perceived by physicians emerged as useful in two ways: first, when the characteristics are organized under implicit theories (Beauvois, 1982; Paicheler, 2011), and, second, when they are compared to the physicians’ own characteristics through the identification process. Additionally, the results stemming fromthe triangulation of the data analyses of the interviews (thematic analysis; (Braun & Clark, 2006) and IPA (Smith, Flowers & Larkin, 2009) highlight the intra-individual differences regarding physicians’ decisions, which is also dependent on the socio-interpersonal context. It helped to broaden the inter-individual difference focus that exists in the literature and therefore contributed to the theoretical development in this field of research. Regarding the SRT, the intra-individual variability of medical decisionmaking revealed by the methodological strategy implemented, allowed cognitive polyphasia phenomena to be brought to light, empirically and in vivo. Medical decision-making emerged, in this context, as a “tensional area” (Kalampalikis & Apostolidis, 2016) where different types of logics and/ or knowledge could compete with each other. Further on, the fifth analytical step, progressively applied based on the results produced by the previous one, informed the diversity and the subtlety of the connections between these different elements of knowledge (i.e., coexisting, conflicting, organized through implicit theories about personality). Also, questioning the rationale of their use through a mixed strategy acknowledged the socio-genesis of this multiple knowledge. The example of the double meaning of the “nice patient” showed that this common-sense knowledge corresponds to traditionally established social codes, norms and values, and the physicians’ direct personal experience of the patient–physician relationship (Jodelet, 2006). The latter appeared particularly worth taking into account for the purpose of capturing the dynamic aspect of the use of patients’ non-medical characteristics in difficult medical decision-making . This idea was reinforced with the analysis of the clinical situations in the fifth analytical step being underlined. This analysis showed how different characteristics were selected to support opposite therapeutic strategies in delicate decisional contexts. These results emphasize the significance of exploring the micro-context of the relationship between individuals to further examine the hypothesis of cognitive polyphasia and to dynamically capture representational phenomena as advocated by the “socio-genetic approach” of the SRT (Kalampalikis & Apostolidis, 2016). Qualitative analyses, therefore, demonstrated that they are appropriate choices for generating empirical and theoretical knowledge. The use of qualitative analyses in our work contrasts with how these analyses are often technically used in mixedmethods design in psychology, where their ability to capture the naturality of phenomena or to contribute to the reconstruction of the meaning individuals make of phenomena is therefore underappreciated. Here we linked quantitative and qualitative analytical procedures guided by the same goal of approaching medical decision-making in oncology from a holistic, contextualized, and “natural” perspective. The theoretical option adopted to achieve this goal and the translation of its epistemological assumptions in themethods and the construction of the analytical procedures made it possible to consistently combine the traditionally opposed qualitative and quantitative analyses in line with the current development in health psychology (Bosisio & Santiago Delefosse, 2014). Instead of a juxtaposition of data coming from different methods, we developed this work from the perspective of a “strong triangulation” (Caillaud&Flick, 2016), using each analytical procedure to capture a different point of view of our studied phenomena. Nevertheless, our perspective of a “strong triangulation” also included pursuing data corroboration. Each analytical procedure was also considered as being of interest for progressively questioning the interpretations developed and orienting subsequent procedures with a view to adding depth rather than validity in the comprehension of the phenomena. In this case, the development of the qualitative analyses did not follow a “ready to use plan” but was based on the theoretical assumptions of the SRT, the research questions, and medical decision-making in oncology particularities. This resulted in a singularmethodological program which cannot directly be exported to other contexts or objects of research (choices of the data collection methods, of the way we combined and chronologically implemented them and similarly for data analyses procedures). However, the development of research seeking a contextualized, complex and dynamic approach to phenomena can be inspired by the rationale underlying the elaboration of this ad hoc procedure. To establish such a procedure, it is not only essential that the researchers immerse themselves in the field but also that they are creative in conceiving innovative methods (e.g., based on the combination of the possibilities offered by real settings and theoretical research goals). The position of a “bricoleur” (Denzin& Lincoln, 2000) researcher and their involvement in the co-construction of participants’ actions meaning-making nevertheless implies the need for an establishment of methodological strategies to limit their pitfalls. Here, the combination of several analytical steps as well as the researchers’ triangulation strategy were used to question the plausibility of the interpretive analyses built up and to balance the inherent limitations of the subjective interpretations of the data. It would be interesting if these different spheres of reflexivity were examined further by extending the multiple triangulation strategy developed through a triangulation of the theories used to interpret the data. Guiding the qualitative development of a mixed methods design, the triangulated strategy conducted in this research allowed us to see how medical decision-making in oncology is complex, dynamic, and intersects tensional aspects. This way of revealing medical decision-making was made possible by using qualitative methodologies from the perspective of an “outdoor psychology”, (Geertz, 1983), which means leaving the social laboratory to explore the richness of real-life situations. Using qualitative methodologies following this perspective and the triangulation strategy would add value to its recognition and visibility in the discipline. These methodological issues nevertheless tend to extend to science in general where the triangulation strategy is becoming for example a recent interest for public health sciences also (Munafo & Davey Smith, 2018). It appears to be a promising alternative paradigm allowing the epistemology of scientific work (e.g., bridging the qualitative-quantitative divide) and of research practices (e.g., enhancing interdisciplinary collaboration) to be reinvented.