Previously we found differences in the distribution of the individual human papillomavirus types in cervical cancers and high-grade squamous intraepithelial lesions. This suggested that there were differences in risk for progression of high-grade squamous intraepithelial lesions that were related to human papillomavirus type within the category of oncogenic genotypes. In this work, we add additional cases including low-grade squamous intraepithelial lesions. ThinPrep samples from 282 squamous intraepithelial lesions and invasive cervical cancers were categorized morphologically by consensus interpretation and genotyped for 27 individual human papillomavirus types by polymerase chain reaction-based reverse line blot analysis using PGMY09/PGMY11 consensus primers for the L1 open reading frame. The 27 human papillomavirus types were divided into three categories: high risk 16, 18, 31, 45; intermediate risk 33, 35, 39, 51, 52, 56, 58, 59, 68, 73, 82, 83; and low risk: 6, 11, 26, 40, 42, 53, 54, 55, 57, 66, and 84. Of the 282 cases of cancer and squamous intraepithelial lesions, 95.7% were positive for one or more of 27 human papillomavirus types and 38.7% had two or more genotypes. Three major categories of squamous intraepithelial lesions were identified based upon the combination of consensus diagnosis and human papillomavirus category: (1) high-grade squamous intraepithelial lesions associated with high-risk human papillomavirus types that appear to be at increased risk for progression to carcinoma; (2) squamous intraepithelial lesions (typically low-grade intraepithelial lesions and high-grade lesions consistent with moderate dysplasia) associated with intermediate risk human papillomavirus types with limited or indeterminate risk for progression; (3) low-grade squamous intraepithelial lesions associated with low-risk human papillomavirus types with little or no risk for progression. Only a subset of human papillomavirus genotypes commonly considered to be oncogenic were closely associated with invasive cervical cancer and high-grade squamous intraepithelial lesions classed as severe dysplasia. Other oncogenic types were closely associated with high-grade squamous intraepithelial lesions of moderate dysplasia and low-grade squamous intraepithelial lesions. This suggests that risk for progression to invasion in squamous intraepithelial lesions is closely related to human papillomavirus genotype. Knowledge of the associated human papillomavirus type in women with morphologic squamous intraepithelial lesions may help to clarify risk for progression.