This thesis explores factors that impact on military personnel and military veterans accessing mental health care. It is widely recognised that military personnel and military veterans are at high risk of developing mental health difficulties. Since military operations in Iraq and Afghanistan, the mental wellbeing of military personnel and veterans has featured prominently as a political, media and public health concern. Military personnel and military veterans do not tend to seek support for their mental health difficulties and consequently do not get the support they may need. In order to address this clinical concern, research has focused on identifying barriers and facilitators to mental health care in this population. This thesis explores these factors within the UK military population in the following two chapters. Chapter one consists of a systematic review of the literature on perceived barriers and facilitators to mental health care in the UK military population. Chapter two details an empirical study that explored how military veterans decided to access psychological support, in order to develop a theoretical model to describe and understand this process.