Profiling students' reading comprehension ability provides essential data to educators to identify students struggling with reading. However, tertiary-level test-takers and test-givers are not always aware of the makeup and design of profiles, which creates real challenges in the use of profiling of test results to diagnose problematic areas in reading. This research hoped to unveil the English reading comprehension ability (ERCA) of first-year undergraduate engineers by employing the Thai Reading Evaluation and Decoding System (T-READS). The sample consisted of 751 first-year undergraduate engineers at a Thai public university. Researchers analysed data using descriptive statistics (i.e., TREADS results) and inferential statistics (i.e., one-way ANOVA). Data analysis led to two major findings. First, the data revealed that 74% of undergraduate engineers were at Band 3 and above, which was the minimum university requirement of ERCA. Second, statistically significant differences in the T-READS scores among four groups of performers (Above Standard, Meet Standard, Below Standard and Academic Warning) (F [3,747] = 1476.66, p = 0.00) were found. Major findings hold pedagogical implications that provide English programme planners at the tertiary level with insights into the reading comprehension difficulties faced by undergraduate engineers and the use of T-READS as a formative assessment tool that can be localized for the planning of targeted interventions.