The construction industry is a major driver of economic growth, employment generation, and infrastructure development in Nigeria. However, persistent delays in project delivery continue to undermine the industry's contribution to national development. This study assessed the causes and effects of construction delays in Katsina and Kazaure towns, Nigeria. A descriptive cross-sectional survey design is proposed, targeting contractors, consultants, architects, engineers, quantity surveyors, builders, and government project supervisors involved in public and private construction projects. A structured questionnaire using a five-point Likert scale would be administered to 200 respondents selected through stratified and purposive sampling techniques. Data would be analyzed using descriptive statistics, Relative Importance Index (RII), mean score ranking, Pearson correlation, and multiple regression. Based on the hypothetical analysis, delayed payment by clients (RII = 0.91), inflation and fluctuating material prices (RII = 0.89), poor project planning (RII = 0.88), shortage of skilled labour (RII = 0.86), and inadequate contractor financial capacity (RII = 0.85) emerged as the leading causes of project delays. The regression model indicates that these factors explain a substantial proportion of the variation in construction delays, highlighting the importance of financial management and project planning in improving project delivery. The study recommends prompt payment mechanisms, improved project planning, contractor capacity development, adoption of digital project management tools, and stronger monitoring by regulatory agencies to minimize delays and improve infrastructure delivery in Northwestern Nigeria. These findings are consistent with recent Nigerian studies that identify client-related, contractor-related, and external economic factors as the principal drivers of construction delays. Keywords: Assessment, Construction delays, project management, infrastructure, Katsina, Kazaure, Nigeria, Relative Importance Index.