Under Title VII, courts may give a mixed motive instruction allowing jurors to determine that defendants are liable for discrimination if an illegal factor (here: race, color, religion, sex, or national origin) contributed to an adverse decision. Recently, the Supreme Court held that to conclude that an employer discriminated against a worker because of age, the Age Discrimination in Employment Act, unlike Title VII of the Civil Rights Act of 1964, requires “but for” causality, necessitating jurors to find that age was the determinative factor in an employer’s adverse decision regarding that worker. Using a national online sample (N = 392) and 2 study phases, 1 to measure stereotypes, and a second to present experimental manipulations, this study tested whether older worker stereotypes as measured through the lens of the Stereotype Content Model, instruction type (but for vs. mixed motive causality), and plaintiff age influenced mock juror verdicts in an age discrimination case. Decision modeling in Phase 2 with 3 levels of case orientation (i.e., proplaintiff, prodefendant, and neutral) showed that participants relied on multiple factors when making a decision, as opposed to just 1, suggesting that mock jurors favor a mixed model approach to discrimination verdict decisions. In line with previous research, instruction effects showed that mock jurors found in favor of plaintiffs under mixed motive instructions but not under “but for” instructions especially for older plaintiffs (64- and 74-year-old as opposed to 44- and 54-year-old-plaintiffs). Most importantly, in accordance with the Stereotype Content Model theory, competence and warmth stereotypes moderated the instruction effects found for specific judgments. The results of this study show the importance of the type of legal causality required for age discrimination cases.