The majority of research in environmental education (EE) has focused on measuring knowledge, attitudes, and behavior using quantitative tools and methods. Few studies have attempted to elicit and characterize children's conceptions of the environment or nature, particularly those resulting from a residential EE experience, which contextualize knowledge, attitudes, and may be used to predict behaviors. Therefore little is known about how physical, socio-cultural, and personal dimensions are reflected in conceptual learning in the context of a guided outdoor program. This study begins to address this relative knowledge void by employing qualitative and phenomenological methods in a grounded theory approach. Interviews, writings and drawings on the topic of nature were collected from 5th grade students before and after a three-day residential outdoor school program conducted on the Oregon coast. Students' responses were analyzed in terms of breadth and depth of their nature conceptions. Individual students' additions to the emergent categories of breadth, including new organisms, habitats, processes, and non-living things, were used to measure change in the breadth of students' nature concepts. Change in depth of students' nature concepts was measured by means of emergent hierarchical typologies representing ideas included in students' understanding of nature. Factors affecting students' learning, including the themes students use to frame their interpretations of nature, emergent misconceptions, references to TV and books, students' interest, and weather, are discussed in terms of their impact on the breadth and depth of students' nature conceptions. Findings indicate almost universal gains in breadth and modest gains in depth of students' nature concepts. Children's preconceived ideas about nature, particularly an idealized view in which nature is seen as the opposite of human environments, appear to play an important role in learning. Graduation date: 2006