The undermining effect of extrinsic reward on intrinsic motivation remains unproven. The key unresolved issues are construct invalidity (all four definitions are unproved and two are illogical); measurement unreliability (the free-choice measure requires unreliable, subjective judgments to infer intrinsic motivation); inadequate experimental controls (negative affect and novelty, not cognitive evaluation, may explain "undermining" effects); and biased metareviews (studies with possible floor effects excluded, but those with possible ceiling effects included). Perhaps the greatest error with the undermining theory, however, is that it does not adequately recognize the multifaceted nature of intrinsic motivation (Reiss, 2004a). Advice to limit the use of applied behavior analysis based on "hidden" undermining effects is ideologically inspired and is unsupported by credible scientific evidence.Key words: intrinsic motivation, cognitive evaluation theory Thirty years have passed since Sushinsky (1975, 1976) raised scientific questions about the then newly reported undermining effect of extrinsic reward on intrinsic motivation. We argued that claims of undermining were premature. We questioned whether undermining effects were attribution phenomena or previously demonstrated negative effects of novel rewards, such as distraction, performance anxiety, frustrating delay, and so on. We suggested that greater attention needs to be paid to how rewards are used in undermining studies and to what behavior is actually rewarded. We specifically questioned the significance of undermining studies using only a single trial of reward. We also questioned the relevance of studies that provided reward contingent on time in activity regardless of what the person does with that time. We suggested that the usual symbolic effects of reinforcement, as commonly used in applied behavior analysis, are positive feedback, not cognitive reevaluation of intrinsic interest.Scores of new studies have been published in the 30 years since Sush-