Despite the potential advantages of cellular manufacturing, most plants with cells have only partially converted their systems. This study examines factors that limit cell penetration within plants using a mail survey of cell users. The existence of service processes, lack of a strong champion who would push the design and implementation of more cells, and low cost of tracking non-cell parts/ products on the plant floor were found to be significant predictors of cell penetration for plants with cells and no plans for further cells. Factors limiting penetration in plants planning to implement further cells could not be determined.