This article reports results of a corpus-based evaluation of 14 syntactic complexity measures as objective indices of college-level English as a second language (ESL) writers' language development. I analyzed large-scale ESL writing data from the Written English Corpus of Chinese Learners (Wen, Wang, & Liang, 2005) using a computational system designed to automate syntactic complexity measurement with 14 measures that have been proposed in second language writing development studies (Lu, 2010). This analysis allows us to investigate the impact of sampling condition on the relationship between syntactic complexity and language development, to identify measures that significantly differentiate between developmental levels, to determine the magnitude at which between-level differences in each measure reach statistical significance, to assess the pattern of development associated with each measure, and to examine the strength of the relationship between different pairs of measures. This research provides ESL teachers and researchers with useful insights into how these measures can be used effectively as indices of college-level ESL writers' language development. (Contains 3 footnotes and 8 tables.)