The article addresses the problem of improving the quality of professionally-oriented English language training in a non-language university given the significant heterogeneity of students' entry-level preparation and the limited classroom time. A modular architecture of ESP programs is proposed, interpreted as a method of constructing autonomous learning blocks synchronized with the logic of mastering profile disciplines, supplemented by a system of diagnostic and formative assessment as a mechanism for continuous correction of learning. It is shown that entry diagnostics in vocabulary, grammar, listening, and reading of professional texts reveal both low average values and high variability of results, justifying the use of multi-level tasks and individualization within modules. Tools of formative assessment integrated into the learning process are described: regular quizzes, self-diagnostic maps, peer review of written works, criterion-based rubrics for public presentations, cumulative portfolio. The effectiveness of the proposed model is demonstrated by comparing groups trained on a linear program and on a modular program with continuous monitoring: after the first semester, a more pronounced growth in professional thesaurus, grammar in a professional context, academic writing, and oral presentation skills was recorded with statistically significant differences and a reduction in the spread of results, interpreted as «pulling up» less prepared students through timely feedback. Analysis of motivational and personal indicators reveals an increase in cognitive and instrumental motivation, enhancement of self-control, and reduction in anxiety, correlating with academic achievements. The final comprehensive check through solving a professional case in English confirms a structural shift in the distribution of levels: the share of students with high and advanced results substantially increases, and the number who did not overcome the threshold sharply decreases; dispersion analysis indicates a significant contribution of the used method. The article's material can be used in designing modular courses and developing assessment tools aimed at evidence-based improvement of professional foreign language communication in a technical university.