The attainment gap, the gap in school exam results between pupils from different social backgrounds, is one of the key challenges in the education system. Differences in school achievement act as a block on social mobility and have real consequences for the life chances of those from disadvantaged backgrounds. Children with poor vocabulary age five are more than twice as likely to be unemployed aged 34. Such differences are not just social in origin, they are also geographical. This report summarises the evidence submitted to the All-Party Parliamentary Group on Social Mobility (APPG) on Social Mobility Inquiry into the Regional Attainment Gap, which ran between November 2017 and June 2018. Amongst the many challenges that the APPG heard regarding the regional attainment gap, this report examined issues regarding early years provision, teacher retention, collaboration and austerity. Despite having the highest proportion of free school meal (FSM) eligible pupils at 26%, disadvantaged students in Inner London perform the best of any region in England. Both Inner and Outer London have the smallest attainment gaps between disadvantaged and non-disadvantaged students. While disadvantaged pupils nationally lag significantly behind average in their school performance, disadvantaged students in Inner London perform about the same as the average student. Government policy has shifted away from focusing on quality early years education to focus more on providing childcare to enable parents to work. [This report was produced with the All-Party Parliamentary Group on Social Mobility (APPG).]