Identifying individuals with mathematical difficulties (MD) is becoming increasingly important in our education system. However, recognising MD is only the first stage in the provision of special educational needs (SEN). Although planning the effective remedial support is vital, there is little consensus on the interventions that are appropriate. There are two main reasons for this: first, MD has a variety of manifestations which appear to change with age; and second, there are many potential causes for the difficulties individuals experience. This paper addresses these issues by reviewing research evidence from three "domains" of psychological research (genetic, cognitive, behavioural), all of which appear to offer insights into potential influences on mathematical ability.