Background: Since the discontinuation of Standard Attainment Tests (SATs) in science at age 11 in England, pupil performance data in science reported to the UK government by each primary school has relied largely on teacher assessment undertaken in the classroom. Purpose: The process by which teachers are making these judgements has been unclear, so this study made use of the extensive Primary Science Quality Mark (PSQM) database to obtain a "snapshot" (as of March 2013) of the approaches taken by 91 English primary schools to the formative and summative assessment of pupils' learning in science. PSQM is an award scheme for UK primary schools. It requires the science subject leader (co-ordinator) in each school to reflect upon and develop practice over the course of one year, then upload a set of reflections and supporting evidence to the database to support their application. One of the criteria requires the subject leader to explain how science is assessed within the school. Sample: The data set consists of the electronic text in the assessment section of all 91 PSQM primary schools which worked towards the Quality Mark in the year April 2012 to March 2013. Design and Methods: Content analysis of a pre-existing qualitative data set. Text in the assessment section of each submission was first coded as describing formative or summative processes, then sub-coded into different strategies used. Results: A wide range of formative and summative approaches were reported, which tended to be described separately, with few links between them. Talk-based strategies are widely used for formative assessment, with some evidence of feedback to pupils. Whilst the use of tests or tracking grids for summative assessment is widespread, few schools rely on one system alone. Enquiry skills and conceptual knowledge were often assessed separately. Conclusions: There is little consistency in the approaches being used by teachers to assess science in English primary schools. Nevertheless, there is great potential for collecting evidence that can be used for both formative and summative purposes.