The learning and assessment in clinical nursing practice can only be understood globally by recognizing the context which surrounds them. This article draws upon a descriptive and exploratory research that explores the concept of three worlds, constructed in a previous study (Freitas, 2007): the world of the school, the clinical world and the professional world. In clinical nursing practice, nursing students should be able to observe and handle the complex dimensions and intersections of these three worlds. This article aims understanding how these three worlds participate and influence the teaching, learning, and assessment process. The methodology is framed in the principles of qualitative research, involving participant observation, focus groups and semi-structured interviews as tools for data collection. The data were processed by content analysis according to the model of Bogdan and Biklen (2003) and Bardin (1979). The key finsdings highlight the existence and the dynamics of the three worlds and allow us to recognize their importance in the educational context of nursing.