English learners (ELs) comprise approximately 10% of kindergarten to Grade 12 students in US public schools, with about 15% of ELs identified as having disabilities. English language proficiency (ELP) assessments must adhere to universal design principles and incorporate universal tools, designed to increase accessibility for all ELs, including those with disabilities. This two-phase mixed methods study examined the extent Grades 1-12 ELs with and without disabilities activated universal tools during an online ELP assessment: Color Overlay, Color Contrast, Help Tools, Line Guide, Highlighter, Magnifier, and Sticky Notes. In Phase 1, analyses were conducted on 1.25 million students' test and telemetry data (record of keystrokes and clicks). Phase 2 involved interviewing 55 ELs after test administration. Findings show that ELs activated the Line Guide, Highlighter, and Magnifier more frequently than others. The tool activation rate was higher in listening and reading domains than in speaking and writing. A significantly higher percentage of ELs with disabilities activated the tools than ELs without disabilities, but effect sizes were small; interview findings further revealed students' rationale for tool use. Results indicate differences in ELs' activation of universal tools depending on their disability category and language domain, providing evidence for the usefulness of these tools.