Objective: Older adults with higher self-efficacy may be more likely to benefit from some cognitive training approaches. We examined whether self-efficacy serves as a mediator or moderator of responsiveness to cognitive speed of processing training (SOPT). Method: We used data from the Staying Keen in Later Life (SKILL) study (N = 128) and the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study (N = 1,400). Both studies assessed cognitive speed of processing (Useful Field of View Test—UFOV) and self-efficacy among community-dwelling older adults who were either randomized to SOPT or control conditions. We constructed regression models examining self-efficacy as a predictor of training responsiveness. Results: Analyses from both studies indicated that participants’ self-efficacy scores were not predictive of training gains from SOPT, as measured by UFOV performance. Discussion: Self-efficacy does not affect older adults’ ability to benefit from cognitive SOPT.