Background: Successful carotid endarterectomy (CEA) and carotid artery stenting (CAS) halve long-term stroke risk but are potentially hazardous. Optimising the carotid intervention pathway may reduce harm. Aims: This thesis used qualitative and quantitative methodologies to identify: hospital-level factors affecting CEA and CAS procedural outcomes; failures in the CEA pathway for improvement; temporal and regional trends in CEA and CAS provision and outcomes; and patient-level factors affecting procedural and long-term outcomes. Qualitative Methods and Results: A systematic review of 124,958 patients showed that large hospitals, serving large populations, with vascular beds, clinical pathways and Vascular Surgeons performing CEA were associated with improved outcomes. An ethnographic study, involving 1,072 hours of observations of the CEA pathway in symptomatic patients, identified 110 patient safety incidents primarily in documentation, public health awareness and the care-providing environment. A Healthcare Failure Mode and Effect Analysis of 65 organisational failures by 13 stakeholders recommended patient education to improve stroke recognition, increasing resources, implementing technology, standardising care and improving communication to optimise the CEA pathway. Quantitative Methods and Results: A 16-year analysis of 68,897 English patients in the Hospital Episode Statistics dataset showed that CEA and CAS age-standardised rates reduced since 2011-2012 with regional variation in provision. Despite temporal improvements in most CEA procedural outcomes, regional variation existed in CEA and CAS outcomes. Prior stroke and congestive heart failure were associated with adverse CEA and CAS procedural outcomes whilst ischaemic heart disease, peripheral vascular disease, diabetes mellitus, chronic renal failure, age 70 years and above and non-White ethnicity were associated with increased CEA risk. Increased deprivation was associated with CEA mortality but did not affect CAS outcomes. Similar risk factors existed for long-term stroke risk following CEA and CAS. Conclusions: Organisational and patient-level factors have been identified for optimising the carotid intervention pathway. Implementing these findings may reduce harm in high-risk patients undergoing carotid interventions, maximising their effectiveness.