Entrepreneurial success is related to many factors, among which, those relating to the psychological dimensions of the successful (or unsuccessful) entrepreneur are often overlooked and rarely studied. In particular, some of the most significant psychological determinants of entrepreneurial success may be rooted in the family of origin, such as the patterns of family communication. Family communication in relation to entrepreneurial success has been the object of some research but only in the context of communication within family businesses. The current study presents the theoretical basis and the stages of development of a tool to measure communication in entrepreneurs' families, irrespective of the fact that those families run their own business or not. The main objective of the study was to evaluate the psychometric parameters (factor structure, reliability, validity) of the proposed Entrepreneur's Family Communication Questionnaire (EFCQ). The tool we propose, though inspired by other existing tools measuring the quality of communication within families, is new as it includes a scale specifically devoted to the quality of the communication related to entrepreneurial behaviors, and hence is expected to be useful in a more comprehensive study of psychological determinants of entrepreneurial success we are presently conducting. The validation study results we obtained are promising and confirm that the proposed tool has good psychometric parameters.