Analysis of covariance (ANCOVA) is a handy, powerful, and versatile statistical technique. It is a cousin of analysis of variance (ANOVA). Both ANOVA and ANCOVA, like all other inferential statistics, attempt to explain the nonrandom association between two or more variables. ANCOVA can be used in all forms of ANOVA with one, two, three, or even four independent variables. Likewise, several covariates can be employed simultaneously to control for extraneous variation. Thus, many ANOVA designs can be improved with ANCOVA. This entry discusses the use, application, and benefits of ANCOVA in communication research, and explains the process for selecting covariates.