After completing undergraduate degrees in Psychology and Medicine, Kapil undertook a combined clinical and academic training in Child and Adolescent Psychiatry at the Institute of Psychiatry. He was awarded a Health Services Research Training Fellowship investigating pathways to care for children at risk of ADHD and was subsequently appointed as a Clinical Lecturer. He completed his PhD during this period and received 3 awards marking a significant achievement in research for work based on his PhD, including the 2003 Royal College of Psychiatrists Research Prize. He was appointed as Senior Lecturer in Child and Adolescent Psychiatry in 2005 and promoted to Reader in 2012 and Professor in 2014.