A model to predict the effect of global and local conformability on grasp static stability is presented. Conformability is defined as the geometric similarity between a workpiece and the smallest polyhedron fit over all contacts. Two conformability metrics, C/sub 1/ and C/sub 2/, that quantify global and local conformability, respectively, are introduced. All stiffness components, including workpiece bulk stiffness, are considered in the model. The two metrics are used to analyze the effect of conformability on grasp static stability via examples. These examples show that grasp stability can increase or decrease with conformability depending on the position of the fingers with respect to the line of action of the externally applied loads. Variation in stability and conformability for different assumptions of finger and workpiece stiffness are also discussed.