The study appraised the degree of necessity and usage of material management methods adopted by small-scale construction firms in Abuja and Lagos State, Nigeria. It identified and examined the factors affecting material management practices, and assessed material management-related factors influencing cost variance. Eighty (80) structured questionnaires was administered on sites supervisor/manager through purposive sampling. Data obtained were analyzed using frequency, percentages, Mean score and relative severity index. The study revealed the most important material management method as site planning and organization (4.95), while employment of security (4.88) was often adopted for effective material management. The study found the most severe factors affecting material management as poor site organization, non-availability of material on sites, material not delivered as per schedule with severity index of (0.958), (0.948) and (0.928) respectively. Inadequate storage facilities (3.69), damaged materials (3.65), Loss of material (3.54), were found as material management factors most influencing cost variance. The study therefore recommends that; proper site organization should be carried out on construction site; materials should be made available on-site with required quantities and delivered as at when due with adequate stacking and storage facilities. More so, there should be adequate storage facilities on construction sites, material damage/ loss of material should be reduced to the barest minimum. The service of a good estimator should be engaged by the firms to mitigate against inaccurate/poor estimation of materials.