Complexity measures in academic writing have experienced a shift from clausal to phrasal indices in recent years. Drawing on a subset of Biber et al. (2011) hypothesized stages of writing development, we explored phrasal complexity across sections of research articles (RAs) in applied linguistics and clinical medicine. A 389,332-word corpus consisting of 80 randomly selected RAs from leading journals in applied linguistics and clinical medicine was compiled for the purposes of the present study. One-way analysis of variance (ANOVA) and independent-samples t-test, as implemented in SPSS (version 25), were employed to find differences across the RA sections and between two groups of academic writers. The findings indicated that RAs in clinical medicine relied more heavily on noun phrase modifiers in all sections than those in applied linguistics, suggesting that the distributional pattern of these linguistic expressions is discipline-independent. The implications of the findings are also discussed.