Responding to the call to build teacher interculturality in more dynamic ways, this paper analyzes developmental trajectories of three pre-service teachers enrolled in a course on language and culture in a master's in second language teaching program at a U.S. university. From a sociocultural theory perspective, the article illustrates the various ways in which the pre-service teachers incorporated (or not) the mediational means available to them. The article findings support the claim about the sociocultural nature of human learning, while the analysis informed by a sociocultural perspective on learning explicates why intercultural learning can be more enriching for some participating pre-service teachers than for others. In line with the sociocultural perspective on human learning, the article highlights the importance of the affective dimension and activity for promoting teacher learning and argues for the need to better understand the process of teachers' application of new understandings into their practice. Besides, the article demonstrates the value of teacher educators' reflection on their work. It ends with pedagogical implications for language teacher educators.