Clinical trials are becoming increasingly international in scope. Global studies pose unique challenges in training and calibrating raters owing to language and cultural differences. Recent findings that poorly conducted interviews reduce study power, makes attention to raters' clinical skills critical. In this study, 109 raters from 14 countries went through a two-step certification process on the Hamilton Depression and Anxiety Rating Scales: (i) an online didactic tutorial on scoring conventions, and (ii) applied clinical training, consisting of small language-specific groups in which raters took turns interviewing patients while observed by an expert trainer, and observation and evaluation of individual interviews. Translators were used when native-language trainers were unavailable. Those who were unable to attend the startup meeting received the training individually via telephone. Results found a significant improvement in raters' knowledge of scoring conventions, with the mean number of correct answers on the 20-item test improving from 14.59 to 17.83, P<0.0001. In addition, raters' clinical skills improved significantly, with the mean score on the Rater Applied Performance Scale improving from their first to their second testing from 10.25 to 11.31, P=0.003. These results support the efficacy of this applied training model in improving raters' applied clinical skills in multinational trials.