People with Adrenal Insufficiency are educated to manage their condition, medication, and stressful episodes. Despite this, there is evidence that knowledge is not always applied during times of acute need and adrenal crisis still occur. Since managing one’s medication is behaviour based, interventions designed to change behaviour may assist people with adrenal insufficiency to adopt the correct regime. Healthcare interventions that increase medication adherence tend to be education based and support the assumption that improving knowledge leads to optimal adherence. To date, such interventions have focused on increasing patients’ knowledge about their condition, how and when to take medication and the consequence of not managing their medications. While much is known about interventions designed to enhance medication adherence there is very little available evidence to inform and help people with Adrenal Insufficiency to manage their medication regimens. Behavioural theory can aid the investigation why this may be the case and can help close the knowledge–behaviour gap to aid development of an intervention to prevent and manage adrenal crisis.