Clay work has long been used in art therapy to achieve therapeutic goals. However, little empirical evidence exists to document the efficacy of such work. The present study randomly assigned 102 adult participants to one of four conditions following induction of a negative mood: (a) handling clay with instructions to create a pinch pot, (b) handling clay with instructions to manipulate it freely, (c) handling a soft stress ball with instructions to toss the ball in a structured manner, or (d) handling a soft stress ball with instructions to manipulate it freely. Self-reports revealed greater mood enhancement following clay handling compared to ball handling. This randomized controlled trial (RCT) documents that clay work has specific efficacy for reducing negative mood states. (Contains 2 tables.)