Certified B Corps (B Corps) are firms characterized by a hybrid purpose and a sustainable business model that combines profit with social impact. Prior quantitative studies on B Corps have mainly analyzed the impact of certification on firm performance, while only a few have tried to analyze the antecedents of certification or high sustainability performance. Regression models have been used in most cases, often with inconsistent results and some research limitations. The aim of this study is to test the presence of different possible combinations of firm-level antecedents leading to a high sustainability performance in B Corps. It applies a configurational approach and a qualitative comparative analysis methodology to search for different combinations of organizational factors (size, age, profitability, certification experience, women on board and the "Born B" factor) that lead to a high sustainability outcome, measured by a B Impact Assessment (BIA). Results indicate the existence of four configurations leading to a high BIA, representing as many kinds of impactful B Corps: Born B, small young ventures, small and medium enterprises, and large firms. These results contribute to the literature by showing that a high sustainability performance in B Corps can be reached through different paths (equifinality) entailing both high and low values of each factor (asymmetry) and depends on how factors are combined (conjunction) rather than on their single effect.