Yapı bilgisi mi yoksa kelime bilgisi mi? Hangisi İngilizceyi yabancı dil olarak öğrenen Türk öğrencilerin İngilizce okuduğunu anlama becerisini daha iyi yorduyor?

This study investigates the relative predictive power of key linguistic knowledge domains on the L2 reading comprehension of Turkish university students. The investigation focuses on three dimensions: vocabulary size (breadth), vocabulary depth (qualitative aspects such as polysemy, collocation, and semantic relations), and syntactic knowledge. A quantitative, cross-sectional, predictive correlational design was adopted. The research was conducted with a large sample of undergraduate students whose first language is Turkish and who study in different departments at a public university in Türkiye. Data were collected over four consecutive weeks during regular class hours by administering one instrument per week. In the first week, a vocabulary size test was administered; in the second week, an association-based vocabulary depth test; in the third week, a standardized grammar (syntax) test; and in the fourth week, a reading comprehension test. Common administration procedures were followed, time limits were controlled, and test security was ensured. Analytically, the study first summarized the distributions of the variables with descriptive statistics and then examined relationships among them using correlations. Finally, hierarchical multiple linear regression was employed to assess the specific and incremental contributions of each predictor to reading comprehension. The findings indicate meaningful and positive relationships between reading comprehension and all three predictors. Model comparisons show that syntactic knowledge was the most significant unique predictor of reading comprehension levels; nevertheless, vocabulary size and vocabulary depth also made independent, complementary contributions. These results suggest that, rather than focusing solely on increasing the number of known words, a balanced instructional approach integrating activities that enrich the qualitative depth of lexical knowledge and strengthen syntactic analysis in reading is likely to be more effective. Beyond offering practical implications for curriculum design, assessment, and placement, the study provides contemporary evidence drawn from a large sample regarding the relative roles of linguistic knowledge components in the Turkish EFL context.