Syntactic complexity across academic research article part- genres: A cross-disciplinary perspective J. Elliott Casal a, * , Xiaofei Lu b , Xixin Qiu b , Yuanheng Wang b , Genggeng Zhang b a Department of Cognitive Science, Case Western Reserve University, 617C Crawford Hall,10900 Euclid Ave, Cleveland, OH, 44106, USA b Department of Applied Linguistics, The Pennsylvania State University, 234 Sparks Building, University Park, PA, 16802, USA article info Article history: Received 15 December 2020 Received in revised form 8 March 2021 Accepted 10 March 2021 Available online 15 March 2021 Keywords: Syntactic complexity Academic research writing Research article part-genres Disciplinary variation abstract This study examined eight measures of syntactic complexity across published research article part-genres (Introduction, Methods, Results, and Discussion) and three social sci- ence disciplines (Applied Linguistics, Psychology, and Economics). The corpus of 240 complete texts was analyzed using a modified version of the Syntactic Complexity Analyzer (SCA), and the measures were compared across disciplinary and part-genre variables using a Two-way MANOVA and a series of follow up MANOVA and ANOVA tests. The findings highlight a significant large effect of both discipline and part-genre on all eight syntactic complexity indices, as well as a significant but small effect size for the interaction of move and discipline on the complexity measures. Important disciplinary and part-genre based differences in the use of syntactically complex structures are discussed, as are the implications of these findings on EAP writing research and pedagogy. © 2021 Elsevier Ltd. All rights reserved. 1. Introduction There is a rich tradition in Applied Linguistics research of utilizing syntactic complexity as a means of measuring and benchmarking learner development (through a large set of indices; see Wolfe-Quintero, Inagaki, & Kim, 1998), and the scope of syntactic complexity scholarship within English for Academic Purposes (EAP) has expanded, as it is increasingly adopted as a means of analyzing the academic writing practices of disciplinary specialists and the texts produced by second language (L2) English student writers. The preponderance of syntactic complexity research overall has targeted the written production of L2 English writers, and such scholarship has considered the interplay between the production of syntactically complex struc- tures in L2 English writing and genre (e.g., Lu, 2011; Staples & Reppen, 2016; Yoon & Polio, 2017), topic (e.g., Yang, Lu, & Weigle, 2015), and writing quality (e.g., Biber, Gray, & Staples, 2016; Bult e & Housen, 2014; Casal & Lee, 2019; Crossley & McNamara, 2014; Kyle & Crossley, 2018; Taguchi, Crawford, & Wetzel, 2013), with many studies emphasizing writing in first-year composition or standardized testing contexts. EAP studies have utilized syntactic complexity as a means of examining a broadening range of topics, such as the use of English as an academic lingua franca (Wu, Mauranen, & Lei, 2020), or comparisons of complex structures in expert and learner texts (e.g., Ansarifar, Shahriari, & Pishghadam, 2018), and interest * Corresponding author. Department of Cognitive Science, Case Western Reserve University, 617C Crawford Hall,10900 Euclid Ave, Cleveland, OH, 44106, USA. E-mail addresses: jec203@case.edu (J.E. Casal), xxl13@psu.edu (X. Lu), xjq5016@psu.edu (X. Qiu), yzw5283@psu.edu (Y. Wang), gzz17@psu.edu (G. Zhang). Contents lists available at ScienceDirect Journal of English for Academic Purposes journal homepage: www.elsevier.com/locate/jeap https://doi.org/10.1016/j.jeap.2021.100996 1475-1585/© 2021 Elsevier Ltd. All rights reserved. Journal of English for Academic Purposes 52 (2021) 100996