ABSTRACT Language accessibility and cultural awareness are essential elements of quality healthcare. Individuals with limited English proficiency are less likely to self-identify a need for behavioral health services, which results in longer duration of untreated disorders. Accurate identification, diagnosis, and treatment are entirely dependent on a linguistically-accurate screening and assessment, especially for sensitive topics such as substance use. Substance use screening in primary care is now recommended as an evidence-based practice for all adults, but remains underutilized. The shortcomings of existing substance use screening tools led the NIH to develop and validate the “Tobacco, Alcohol, Prescription drug, and illicit Substance use Tool (TAPS Tool), a two-stage screening and brief assessment tool to detect substance use problems in primary care. As part of our Phase I NIMHD STTR project, our team led a research-driven adaptation of the TAPS Tool into a Spanish language version, and developed a mobile/tablet technology platform to support its deployment in healthcare settings (the TAPS-Electronic Spanish Platform, or TAPS-ESP). The current Phase II SBIR study builds on this effort. For Aim 1, we will integrate the TAPS-ESP into the existing health information technology infrastructure of Baylor Scott and White Health (BSWH), a large healthcare system in Texas that serves a large number of Spanish-speaking patients. For Aim 2, we will conduct a large-scale validation study of the TAPS-ESP against a widely-used diagnostic reference standard, other screening tools, and oral fluid/saliva drug testing in a large sample of 1,000 Spanish-speaking primary care patients. Separately, for Aim 3 we will conduct a real-world implementation trial in which 10 primary care providers receive training on the TAPS-ESP, incorporate it into standard care, and complete a qualitative interview on barriers and facilitators of implementation from a provider workflow perspective. To the best of our knowledge, this will be the largest validation study of a Spanish-language substance use screening tool in the US to date. The project could expand access to evidence-based, linguistically-accurate substance use screening and brief assessment for an underserved population that experiences significant behavioral health disparities. Thus, the project could have high scientific and public health impact, along with strong commercialization potential.