High dropout rates threaten the validity of longitudinal studies involving participants suffering from substance use disorder (SUD). The objective of this article is to evaluate strategies to improve retention. The data analysis was based on an ongoing study of long-term recovery of neurocognitive and psychosocial functions. We used traditional strategies to enhance the contact rate. Common factors in psychosocial treatments and biweekly Short Message Service (SMS; text messaging) monitoring were added to further increase the contact rate. The participants (n = 146) were recruited from treatment facilities for SUD. Assessments were measured at 3 months, 6 months, 9 months, and 12 months. This study was successful in retaining a cohort of participants who are typically characterized as having a negative prognosis because of their unstable living arrangements and incomes. Compared to those using GHB, addictive medications, and opiates, the retention rate was the lowest among participants with severe alcohol use disorder (42%).