Patients with insomnia respond best to cognitive-behavioral treatments (CBT) if they find the approach acceptable. One tool, the Insomnia Treatment Acceptability Scale (ITAS), has been used to identify such patients, however, its reliability and validity has not been well established especially in primary care. The purpose of this study was to assess the reliability and validity of the ITAS in a primary care setting. A cross-sectional survey was conducted with 236 primary care patients, aged 18 and above, with clinically significant insomnia (Insomnia Severity Index ≥8). Descriptive and summary statistics, Cronbach's alpha, Principal Axis Factor analysis with Promax rotation, and comparison of ITAS subscale scores with self-reported treatment preferences (Chi-Square) are included. Factor analysis identified two factor solutions for the ITAS subscales. The ITAS was shown to be a reliable and valid tool that can be used to facilitate psychological practice and research on interdisciplinary behavioral-medical care.