This study tracks the development of syntactic complexity in the writing of two beginning German as a second language learners with English as a first language over four semesters of collegiate language study by using developmental profiling techniques applied to an annotated learner corpus. The focus of the investigation is on individual developmental pathways and differences between learners who follow the same instructional sequences. The study explores variation in terms of frequencies of the selected complexity features (coordinate, nominal, and nonfinite verb structures) using corpus analysis techniques with semi-automatic corpus annotation. Two developmental profiles emerge from an in-depth contextual investigation of the target linguistic phenomena. The results show that the general developmental trend is for increasing frequency and range of syntactic complexity features with learners diverging more from one another in the second half of the observation period. This study addresses existing gaps in interlanguage complexity research by focusing on benchmarking development rather than gauging proficiency, addressing specific rather than global complexity measures, and targeting instructed learners at beginning rather than high-intermediate and advanced proficiency levels. Suggestions for future developmental second language acquisition research and foreign language pedagogy are made.