The Effect of Gamma Rays on Man-in-the-Moon Marigolds is a 1972 American drama film produced and directed by Paul Newman. The screenplay by Alvin Sargent is based on the Pulitzer Prize-winning 1964 play of the same title by Paul Zindel. Newman cast his wife, Joanne Woodward, and one of their daughters, Nell Potts, in two of the lead roles. Roberta Wallach, daughter of Eli Wallach, played the third lead.