Labor productivity has a profound impact on construction management. The accurate prediction of productivity is essential to effectively plan operations that depend on time and cost and is critical for the success of a construction project for both the contractor and the owner. However, predicting productivity of operations is challenging due to the multiple characteristics of workers, the interrelationships between workers, and the site conditions that impact the performance of crews and affect project goals. This paper proposes a methodology to quantify the factors that affect productivity in masonry construction. We have considered three factors: compatibility, suitability, and craft. Standardized data-collection techniques are used to consolidate data from three masonry sites and mathematically define a productivity function that relates workers characteristics and crews with site conditions. The function, increasing in its arguments, determines the factors that most affect masonry productivity and the factor's effects. The most interesting part is to be able to identify the convexity properties of this function because its theoretical interpretation will have implications on the impact of the superintendent's decisions when forming crews. The proposed mathematical function can enable superintendents to better plan, schedule, and manage masonry crews.