AbstractMuseum educators have a longstanding presence in museums and play a significant role in the institutions' educational agenda. However, research on field trips to science museums has predominantly explored teachers' and students' perspectives with little acknowledgment of the museum educators who develop and implement the educational programs the students experience. This study sought to describe instruction undertaken in, and goals driving, science museums' lessons through observations of museum educators followed by conversations with them immediately afterwards. Findings showed the ways in which educators adapted their preplanned lessons to the students' interests, needs, and understanding by manipulating the sequence and timing. The data revealed that, contrary to depictions in the research literature of teaching in museums as didactic and lecture oriented, there was creativity, complexity, and skills involved in teaching science in museums. Finally, the educators' teaching actions were predominantly influenced by their affective goals to nurture interests in science and learning. Although their lessons were ephemeral experiences, these educators operated from a perspective, which regarded a school field trip to the science museum, not as a one‐time event, but as part of a continuum of visiting such institutions well beyond school and childhood. These findings have implications for the pedagogical practices employed by museum educators, and the relationship between teachers and educators during school field trips, which are discussed. © 2006 Wiley Periodicals, Inc. Sci Ed 91:278–297, 2007