Background: Over the last few decades, evidence-based treatments for emerging adults with drug use disorder (DUD) have been developed, but dropout and inconsistent session attendance persist. This study assessed the efficacy of voucher reinforcement and/or text reminders for treatment attendance and completion in emerging adults with DUD in Denmark., Methods: The study compared four levels of treatment intensity, with participants randomly assigned to standard outpatient counseling only (STD), outpatient counseling plus vouchers for attendance (VOU), outpatient counseling plus text reminders (REM), or outpatient counseling plus vouchers and text reminders (REM + VOU). A total of 460 individuals aged 15-25 years seeking treatment for DUD were randomly assigned to the four treatment conditions across nine sites., Results: STD counseling had the lowest completion rate (25%), followed by REM (39%), VOU (46%), and REM + VOU (49%). Additionally, post hoc comparisons indicated that clients randomized to the REM + VOU condition differed in terms of zero no-shows from clients who were randomized to the VOU condition (χ2(1) = 6.90, p = 0.009) and the REM condition (χ2(1) = 5.87, p = 0.015)., Conclusions: Vouchers and text reminders contribute to reduced dropout and increased treatment attendance in emerging adults with DUD. The combination of vouchers and reminders in particular has the potential to reduce the number of no-shows., (Copyright © 2020 Elsevier B.V. All rights reserved.)