In December of 2003, the Project Management Institute (PMI) published a new project management standard focused on the organizational level. The Organizational Project Management Maturity Model (OPM3), presents a disciplined and systematic means for organizations to reach a higher level of project maturity based upon an extensive array of project management best practices and capabilities. OPM3 encompass three general elements: (a) knowledge, stating the content of the standard, (b) assessment, a method to appraise the organization against OPM3, and (c) improvement, preparing the stage for possible organizational changes. However, the improvement element presents a major challenge because it comprise a package of values, preferences, attitudes, and other artifacts, which also form part of any organizational culture. OPM3 does not consider organizational culture (OC) as part of the model. This book explore the opportunity of integrating OC with OPM3 and any correlations between these two. Finally the author demonstrates that including OC as part of the OPM3 exercise will add an important piece of information to successfully managing organizational improvements sustainability.