Base-line data on a series of risk indicators were related to 11-month caries increment in 181 subjects with a mean age of 13 years and 3 months. A caries increment equalling or exceeding one tooth surface was recorded in 21% of die subjects. The risk indicators consisted of past caries experience, white spot lesions, visible plaque and gingivitis, and six salivary tests: secretion rate, buffer effect, sucrase, mutans streptococci, lactobacilli, andCandida. Significant associations between caries increment and past caries experience (p= 0.002), white spot lesions (p= 0.01), lactobacilli (p= 0.02),Candida(p= 0.006), and sucrase (p= 0.02) were observed. The ensuing odds ratios were thus recorded: past caries experience, 3.6; white spot lesions, 2.9; salivary sucrase activity, 2.9; lactobacilli, 2.5; andCandida, 2.8.