margins is a powerful postestimation command that allows the estimation of marginal effects for official and community-contributed commands, with well-dened predicted outcomes (see predict). While the use of factor-variable notation allows one to easily estimate marginal effects when interactions and polynomials are used, estimation of marginal effects when other types of transformations such as splines, logs, or fractional polynomials are used remains a challenge. In this article, I describe how margins's capabilities can be extended to analyze other variable transformations using the command f able.