Catch Up® Numeracy is a one to one intervention for learners who are struggling with numeracy. It consists of two 15-minute sessions per week, delivered by teaching assistants (TAs). The approach is based on research indicating that numeracy is not a single skill, but a composite of several component skills that are relatively discrete. The intervention breaks numeracy down into ten elements, including counting verbally, counting objects, word problems and estimation. Pupils are assessed on each component and instruction is targeted on those areas requiring development. In this evaluation, the intervention was run for 30 weeks and delivered to Year 2-6 pupils who were struggling with numeracy, as identified by TAs. The Catch Up Numeracy intervention was compared to a 'business as usual' control group and a 'time equivalent' intervention group, who received the same amount of one to one teaching by TAs, but did not use Catch Up Numeracy. Those TAs delivering Catch Up Numeracy were supplied with detailed session plans and received three half-day training sessions, led by Catch Up and Dr Ann Dowker of the University of Oxford. The project ran from September 2012 to July 2013. [The project was independently evaluated by a team from the National Foundation for Educational Research, led by Simon Rutt.]