Since the early 1980s, a number of initiatives have been undertaken worldwide which have involved scientists and teachers working together in projects designed to support the science learning of students. Many of these have attempted to establish school-scientist partnerships. In these, scientists, teachers, and students formed teams engaged in mutually beneficial science-based activities founded on principles such as equal recognition and input, and shared vision, responsibility and risk. This article uses two partnership programmes run by a New Zealand Science Research Institute, to illustrate the challenges faced by scientists and teachers as they attempted to forge meaningful and effective partnerships. It argues that achieving the theorised position of a "shared partnership space" at the intersection of the worlds of scientists and teachers is problematic, and that scientists must instead be prepared to penetrate deeply into the world of the classroom when undertaking any such interactions. Findings indicate epistemological differences, curriculum and school systems and issues, and teacher efficacy and science knowledge significantly affect the process of partnership formation. Furthermore, it is argued that a re-thinking of partnerships is needed to reflect present economic and education environments, which are very different to those in which they were originally conceived nearly 30 years ago. It suggests that technology has an important role to play in future partnership interactions.