Five colposcopic signs (thickness, color, contour, vascular atypia, and iodine staining) were graded into three objective categories representing (1) subclinical papillomaviral infection, (2) lower-grade dysplasia, and (3) grade 3 cervical intraepithelial neoplasia. Seventy-two colposcopically different biopsy specimens (25 of subclinical papillomaviral infection and 18 of grade 1, 18 of grade 2, and 11 of grade 3 cervical intraepithelial neoplasia) were collected from 52 women and interpreted by validated, quantitative histologic analysis. Attempts to grade lesions by the prominence of the acetowhitening reaction or the mere presence of aberrant surface capillaries were unsuccessful. In contrast, each of five new colposcopic criteria were significantly correlated with histologic severity. Differences in color, vascular atypia, and iodine staining were more predictive than those of thickness and contour. Combined into a weighted index, these colposcopic features were 96% correct in forecasting approximate histologic findings. Because this method relies upon critical analysis rather than pattern recall, the use of this colposcopic index greatly simplifies the learning of colposcopy.