Providing high-magnitude cash incentives to substance abuse clients to participate in research is frequently viewed as unethical based on the concerns that this might precipitate new drug use or be perceived as coercive. We randomly assigned consenting drug abuse outpatients to receive payments of $10, $40, or $70 in either cash or gift certificate for attending a 6-month research follow-up assessment. At the 6-month follow-up, participants received their randomly determined incentive and were then scheduled for a second follow-up appointment 3 days later to detect new instances of drug use. Findings indicated that neither the magnitude nor mode of the incentives had a significant effect on rates of new drug use or perceptions of coercion. Consistent with the contingency management literature, higher payments and cash payments were associated with increased follow-up rates. Finally, the results suggest that higher magnitude payments may be more cost-effective by reducing the need for more intensive follow-up efforts. © 2004 Elsevier Ireland Ltd. All rights reserved.