We enhance the theoretical precision of cultural intelligence (CQ: capability to function effectively in culturally diverse settings) by developing and testing a model that posits differential relationships between the four CQ, dimensions (metacognitive, cognitive, motivational and behavioural) and three intercultural effectiveness outcomes (cultural judgment and decision making, cultural adaptation and task performance in culturally diverse settings). Before testing the model, we describe development and cross-validation (N = 1,360) of the multidimensional cultural intelligence scale (CQS) across samples, time and country. We then describe three substantive studies (N = 794) in field and educational development settings across two national contexts, the USA and Singapore. The results demonstrate a consistent pattern of relationships where metacognitive CQ and cognitive CQ predicted cultural judgment and decision making; motivational CQ and behavioural CQ predicted cultural adaptation; and metacognitive CQ and behavioural CQ predicted task performance. We discuss theoretical and practical implications of our model and findings.