OBJECTIVES: The goal of the current study was to assess the treatment patterns (adherence, persistence, augmentation, and switching) in preschoolers diagnosed with ADHD using the Texas Medicaid dataset. METHODS: Texas Medicaid claims between January 01, 2008 and August 01, 2013 was used for the study. The index date was the date of the first ADHD prescription after diagnosis. The study sample included treatment-naïve patients between 2 and <6 years of age at index, with (1) at least one ADHD diagnosis based on ICD-9 codes (314.0x): (2) at least two ADHD medication claims; and (3) continuous enrollment in the index period. The study sample was sub-divided into two groups based on follow-up period therapy: pharmacotherapy only and combination therapy. The dependent variables were: adherence (measured as proportion of days covered); persistence (duration of therapy without a gap of >30 days); augmentation (initiation of a new ADHD medication with a continuous overlap of ≥30 days with the index medication); and switching (prescription claim for an alternative ADHD medication received on or after the index date), before or within 30 days of discontinuation of the index medication. Multivariate analyses were used to assess the treatment patterns among treatment groups. RESULTS: Of the 8,833 preschoolers identified in the study, pharmacotherapy group patients had 11.1% lower odds of adherence (Odds Ratio [OR] = 0.889; 95% Confidence Interval (CI) = 0.799–0.988; p = 0.03), 26.2% lower odds of augmentation (OR = 0.738; CI = 0.642–0.850; p < 0.0001), and 20.2% lower odds of switching (OR = 0.798; CI = 0.725–0.878; p < 0.0001) compared to combination therapy group patients, while controlling for covariates. Discontinuation of medication therapy did not differ significantly between the treatment groups. CONCLUSIONS: Comparison of treatments revealed that the combination therapy group had higher adherence, persistence, and augmentation compared to the pharmacotherapy group.