The aim of this paper is to assess the construction project planning practices of Defense Construction Enterprise. As such, the study examines the planning practice; the first part exploring the underlying factors influencing them and the second part, examining the level of advancement of existing planning practices, simultaneously assessing their perceived degree of impact on successful project completion. In light of these, the research intended to discover the least advanced and yet the most impactful planning practices, requiring the enterpriseâ€™s priority and mobilization of efforts for improvement. After a detailed literature review and desk study, 30 possible factors influential to project planning were identified and grouped into six major categories based on the nature of the factors. This was followed by determination of 13 general planning practices, nine of which are adopted from planning knowledge areas as per PMI (2008), and the remaining were included to put project management in the context of construction management. Subsequently, 42 specific planning practices were identified. All 30 factors and 42 planning practices were included in a three part questionnaire survey with an unstructured interview designed to supplement questionnaire results. As such, 41 questionnaire responses and 4 interviews were collected and conducted respectively, from enterprisesâ€™ practitioners and senior planning engineers involved in 14 substantially completed projects undertaken by the enterprise in the last decade. Subsequently, the Relative Importance Index (RII) was used to rank levels of advancement, impact and criticality of practices, using SPSS software. The research found, amongst 30 factors; shortage of time for planning, unrealistic or short contract duration and giving no or little attention for identification & allocation of potential risks were the most influential factors affecting planning practices of the enterprise. Management and time related factors were generally found to have the highest influences. From the 42 planning practices; identification of major/special supply items especially shipped from overseas, inclusion of design changes in revised plans during execution phase and special consideration of critical items/materials requiring long-lead times, were the least advanced and simultaneously those having the greatest impacts on successful completion of projects. Relatively, it was found that procurement, scope and integration planning practices required the enterpriseâ€™s utmost priority and mobilization of efforts for improvement.