The purpose of the study was to apply various quantitative and qualitative indices of grammatical complexity proposed by Hunt (1965) to written language samples of hearing impaired students. Hunt studied grammatical structures of normal students at three grade levels, and found that the minimal terminal syntactic unit, or T-Unit, more reliably measured increasing syntactic complexity than the Subordination Ratio commonly used. Part I of the investigation studied the T-Unit as a measure of syntactic complexity in the written language of 23 males and 23 females at nine selected age levels (10-18 years). The Subordination Ratio appeared to be more useful and reliable than the T-Unit, which, however, did prove to be a useful measure. Part II of the study examined the types of grammatical structures which were chief contributors to increasing syntactic complexity in the written language samples. It was found that certain types of verbs and verbals possessed a great deal of sensitivity to growth across the whole 9-year age span sampled, while other constructions tended to be sensitive only at the younger or only at the older ages. (Author/KW)