This research investigates the potential benefits of a fair co-branding operation. Two major corporate brands are fictitiously allied with a Fair Trade labeling organization brand. The sample for the first study is composed by 540 interviews, and by 350 for the second study; it is representative of the French population. Besides showing that the paradigm of co-branding is consistent to evaluate brand alliances between corporate and Fair Trade brands, the PLS model implemented in this research first investigates how do classical variables (attitudes, fit, similarity) are antecedents of co-branding relevancy and customers’ evaluation of the alliance. Second, this study introduces a new explicative variable based on the similarity-dissimilarity of the brands on FairTrade related aspects. The results obtained through the test of a PLS (Partial Least Square) model are a first step to better understand co-branding between corporate and labeling brands. This study also provides findings concerning the whole paradigm of cooperation between profit and non-profit organizations. In this type of brand alliance, the corporate brand provides the alliance with its leading position, and the Fair Trade brand provides the ethical attribute.