VV&A (Verification, Validation and Accreditation) and Conceptual Modelling (CM) are two closely related fields within M&S (Modelling and Simulation). The purpose of this study is to assess two methodologies, REVVA and DCMF, within VV&A and CM, respectively, on each other. The expected benefits from the study are to identify the strength and weakness of the methodologies, and to provide the findings as input for improving these methodologies that are still in the process of development. It has been shown that REVVA and DCMF are compatible with each other. In particular an interface between the approaches has been defined in terms of dependency between their products. This interface is then suggested as a link between VV&A and CM. REVVA and DCMF provide indeed a simple but informative overview of the process and the products of VV&A respectively CM, which is quite helpful to understand the whole spectrum of the fields. On the other hand, both methodologies suffer from immaturity, and much work has to be done for the methodologies to meet the real needs from people practising in VV&A and CM. From the REVVA-DCMF common viewpoint, first and foremost, the syntax and the semantics of their core products, i.e. Target of Acceptance, Target of V&V, Items of Evidence (REVVA products) and Mission Space Model (DCMF product), must be improved significantly.