Objective: Although the benefits of in-person Diabetes Prevention Program (DPP) classes for diabetes prevention have been demonstrated in trials, effectiveness in clinical practice is limited by low participation rates. This study explores whether text message support enhances weight loss in patients offered DPP classes., Research Design and Methods: English- and Spanish-speaking patients with prediabetes (n = 163) were randomized to the control group, which only received an invitation to DPP classes as defined by the Centers for Disease Control and Prevention, or to the text message-augmented intervention group, which also received text messages adapted from the DPP curriculum for 12 months., Results: Mean weight decreased 0.6 pounds (95% CI -2.7 to 1.6) in the control group and 2.6 pounds (95% CI -5.5 to 0.2) in the intervention group (P value 0.05). Three percent weight loss was achieved by 21.5% of participants in the control group (95% CI 12.5-30.6), compared with 38.5% in the intervention group (95% CI 27.7-49.3) (absolute difference 17.0%; P value 0.02). Mean glycated hemoglobin (HbA1c) increased by 0.19% or 2.1 mmol/mol (95% CI -0.1 to 0.5%) and decreased by 0.09% or 1.0 mmol/mol (95% CI -0.2 to 0.0%) in the control group and intervention participants, respectively (absolute difference 0.28%; P value 0.07). Stratification by language demonstrated a significant treatment effect in Spanish speakers but not in English speakers., Conclusions: Text message support can lead to clinically significant weight loss in patients with prediabetes. Further study assessing effect by primary language and in an operational setting is warranted., (© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)