Objectives: This report describes the training of dental examiners participating in two dental caries clinical trials and reports the inter- and intra-examiner reliability scores from the initial standardization sessions. Methods: Study examiners were trained to use a modified International Caries Detection and Assessment System II system to detect the visual signs of non-cavitated and cavitated dental caries in adult subjects. Dental caries was classified as no caries (S), non-cavitated caries (D1), enamel caries (D2), and dentine caries (D3). Three standardization sessions involving 60 subjects and 3,604 tooth surface calls were used to calculate several measures of examiner reliability. Results: The prevalence of dental caries observed in the standardization sessions ranged from 1.4 percent to 13.5 percent of the coronal tooth surfaces examined. Overall agreement between pairs of examiners ranged from 0.88 to 0.99. An intra-class coefficient threshold of 0.60 was surpassed for all but one examiner. Inter-examiner unweighted kappa values were low (0.23-0.35), but weighted kappas and the ratio of observed to maximum kappas were more encouraging (0.42-0.83). The highest kappa values occurred for the S/D1 versus D2/D3 two-level classification of dental caries, for which seven of the eight examiners achieved observed to maximum kappa values over 0.90. Intra-examiner reliability was notably higher than inter-examiner reliability for all measures and dental caries classifications employed. Conclusion: The methods and results for the initial examiner training and standardization sessions for two large clinical trials are reported. Recommendations for others planning examiner training and standardization sessions are offered. © 2011 American Association of Public Health Dentistry.