Abstract:The existing literature on citation use generally focuses on the rhetorical functions and textual forms of citations in research writing, hence a lack of systematic look into the citation competence and developmental features on the part of student writers.The present study first defines the constructs of citation competence from its ideational, interpersonal and textual dimensions.By cross-sectional and longitudinal analysis in the comparison of student writing with professional writing, the study explores the developmental features of citation competence in the Chinese BA, MA and PhD theses of applied linguistics.The study finds that (1) the ideational aspect of citation keeps increasing, but the focus of what to cite seems unclear in each section of the research writing.(2) The interpersonal aspect does not develop until students reach the doctoral stage when they are able to enhance connections between sources.(3) The textual competence does not progress significantly.The longitudinal case study further reveals individual differences.The results have some implications for theorizing L2 academic writing, strengthening research methodology and improving writing pedagogy.