In the conditions of the dynamic transformation of communicative practices at the beginning of the 21st century, slang in the English language as a global means of communication ceases to be perceived as a marginal element and actively penetrates various discursive spheres, including journalism, business communication, and informal academic genres. This phenomenon exacerbates the problem of developing learners’ ability to make conscious choices of language registers, since the existing discrepancy between normatively oriented teaching materials and real language experience in digital media leads to violations of stylistic appropriateness in speech and a deficiency in sociolinguistic competence. A comprehensive study, which includes content analysis of popular educational and methodological complexes, diagnostics of the level of slang vocabulary acquisition, and a pedagogical experiment involving 365 schoolchildren and students, reveals the quantitative parameters of this gap: the average proportion of slang units in glossaries constitutes 6.61 percent compared to 12.31 percent of texts containing their elements, with an even more pronounced lag observed in Russian teaching aids. Diagnostic data demonstrate marked thematic heterogeneity in knowledge, whereby Internet slang is mastered significantly more effectively than culturally conditioned units of British and American origin. This creates a distorted perception of learners’ communicative readiness. The results of the quasi-experiment using a module oriented toward the integration of slang in the context of register differentiation record a significant increase in lexical-semantic knowledge indicators (an average of 11.5 points) and in the ability for stylistic interpretation (7.5-9.8 points) in the experimental groups compared with the control groups. This is accompanied by a twofold reduction in the proportion of stylistic errors in written speech. Correlation analysis identifies strong positive correlations between slang competence, register sensitivity, and overall language proficiency, alongside a negative correlation with the number of stylistic violations. These findings refute traditional notions regarding the destructive influence of informal lexis. The dynamics of subjective assessments confirm increased motivation, greater confidence in the use of variable linguistic means, and the emergence of a demand for systematic study of the functional stratification of language. Thus, the materials of the article make it possible to identify the key mechanisms by which targeted work with slang influences the development of integrated linguistic competence and to evaluate the prospects for methodological renewal of educational practices in line with current communicative realities of the digital age. This determines the advisability of consulting the full text for detailed recommendations on implementing appropriate modules in both secondary and higher education.