Project Portfolio Risk Assessment (PPRA) is oriented to provide information on the risk composition at the portfolio level in supporting of the risk response plan. While diverse aspects to be considered for PPRA have been recognized in literature, a comprehensive PPRA incorporating both risk factor interdependency and the impact on portfolio success from a practical perspective remains scarcely explored. This thesis aims to develop knowledge to guide the PPRA design in a way that risk factor interdependency and their impacts on the project portfolio success dimensions can be considered. Based on a systematic literature review, 80 papers were analyzed by conducting conventional content analysis. The analysis led to define and characterize four constructs associated with PPRA, namely, ‘components for PPRA’, ‘PPR categories’, ‘project portfolio success dimensions’, and ‘risk assessment method’. The integration of these constructs resulted in a literature-based framework for PPRA design. Based on this framework, twenty-eight semi-structured interviews were conducted with Colombian professionals with experience related to project portfolio management in organizational development project portfolios. Thus, a conceptualization of a comprehensive PPRA in portfolios of organizational development portfolios is proposed. It integrates six interdependent themes through which practitioners’ perspective can be represented and four propositions that emerged from discussion of the findings. In the last research phase, an analytical model to put in practice the conceptualization of PPRA is proposed. The model is based on a network-based approach and ISM-MICMAC method. The analytical model for PPRA was applied to a project portfolio case study to evidence its practical use. The present study makes several contributions: extending the conceptualization of the type of impact derived from risk factors; adopting organizational capabilities to be generated by the portfolio as a construct for PPRA; posing a risk assessment orientation towards portfolio success dimensions associated with project portfolio effectiveness; and introducing an analytical PPRA model. From a practical perspective, the PPRA conceptualization proposed represents a comprehensive view of characteristics and aspects to be considered for conducting PPRA in practice, which can be operationalized following the analytical PPRA model proposed.