An empirical study was designed to identify which perceptual-motor, cognitive and personality factors may underlie both acquisition of a signed language as a B language and development of signed-language interpreting skills. If abilities that are potentially needed are found, a previous assessment of candidates’ potential for developing signed-language interpreting skills could be useful in identifying which students are likely to obtain good results during training. Perceptual-motor and cognitive skills, personality factors and academic background were hypothesized as possible predictors of success. Results showed that perceptual-motor and cognitive abilities are more important than personality traits at predicting proficiency in learning a signed language and developing signed-language interpreting abilities. Perceptual-motor coordination is the most reliable factor for predicting signed language proficiency, followed by other cognitive and personal factors.