In this article, the authors introduce the Improving Science Together (IST) project (2000-2002), funded by the AstraZeneca Science Teaching Trust. The project was a partnership between 20 primary and 4 secondary schools in Bristol and South Gloucestershire, LEA advisory staff, BAE Systems, and the primary science team at Bath Spa University College. The IST project had as its main focus the development of scientific enquiry and formative assessment in participating schools. The cross-phase transfer element of the project considered how primary schools could provide formative assessment information on children's achievements in scientific enquiry to secondary schools. The authors decided on an approach involving primary and secondary teachers working collaboratively to plan a year 6-year 7 "bridging project". The collaborative planning of the bridging project involved discussions about the detail of lesson planning. This enabled participants (teachers, lecturers and LEA advisers) to explain the approaches they would take in their teaching and a real shared understanding to develop. The project has been successful for the project schools in that it has supported the transfer of meaningful formative assessment information on children's achievement in scientific enquiry. (Contains 4 figures.)