Research about the effectiveness of different types of feedback in programmed instruction was investigated. Knowledge of results had the least data to support its efficacy. Knowledge of correct responding (KCR) has been shown to be effective in several studies. Elaboration feedback is more effective than KCR, but may require more time of the instructional designer and learner. Delayed and review feedback are no better than KCR. Postfeedback delays show promise and warrant further study. Future research area recommendations include: measures of the approachability of instruction, measures of efficiency, sampling from more diverse populations, research over more extended time frames, and exploring the relationship between performance during instruction and on criterion tests. (Contains 1 table.)