In this research, a model for estimating construction cost of villas is presented. The model takes into account four major factors affecting villa's cost, namely: built up area, number of toilets, number of bedrooms and the number of stories. A field survey was conducted to collect information required for such model using data collection form designed by the researchers. Information about 150 villas was collected from six well experienced consultants in the field of villa design and supervision in Oman. Collected data was analyzed to develop suggested model which consists of two main levels of estimate. The first level is at the conceptual design stage where the client presents his/her need of space and basic information about the available plot for construction. The second level of cost estimation is carried out after the preliminary design stage where the client has to decide on the finishes and type of structure. At the second level of estimation, the client should be able to decide whether to precede for construction or not, according to his/her budget. The model is general and can be used anywhere and was validated for accepted degree of confidence using the actual cost of the 112 executed villa projects in Oman. The villas included in this study were owned by clients from both high and low income brackets and had different types of finishing material. The developed equations showed good correlation between the selected variables and the actual cost with R2  = 0.79 in the case of conceptual estimate and R2  = 0.601 for preliminary estimate.