This paper describes a heuristics-based system for automatic measurement of syntactic complexity using the revised Developmental Level (D-Level) Scale (Rosenberg and Abbeduto, 1987; Covington et al., 2006). The system takes a raw sentence as input and assigns it to an appropriate developmental level (0-7). The system is designed with child language acquisition and psycholinguistic research in mind, and is therefore developed and evaluated using child language acquisition data from the CHILDES database (MacWhinney, 2000). Experiment results show that the model achieves an accuracy of 93.2% on unseen spoken data.