A key worker is a public sector employee who is considered to provide an essential service. The term is often used in the United Kingdom in the context of those essential workers who may find it difficult to buy property in the area where they work.
In particular, it has become more prominent as escalating house prices result in a gap between household income and the cost of housing. Many local authorities and other public sector bodies (especially in London and the South East, where a "Key worker living scheme" operates) face major problems recruiting and retaining their workers (many of whom are on lower levels of pay than the private sector) in terms of housing (in most cases the social rented sector is unable to provide low cost housing for rent or shared ownership). The response to these concerns has been the development of initiatives designed to house key workers, including low-cost loans and shared ownership schemes.
Those defined as key workers generally include:
- Clinical National Health Service staff (except doctors and dentists)
- Teachers and nursery nurses
- Police officers, Community Support Officers and some civilian police staff
- Prison officers and some other Prison staff
- Probation Service staff
- Social workers, educational psychologists, and therapists
- Local Authority Planners
- Connexions Personal Advisers
- Some Ministry of Defence personnel
- Environmental Health Officer
- Highway Agency Traffic Officers
The definition is sometimes extended to include those support staff without whom the above roles may struggle to function. The term was also initially used in mental health services to identify the health professional responsible for the coordination of care under CPA, but has since been replaced in 1999 by the term Care Co–ordinator 
- "Key Worker Living programme", Directgov
- "Key worker living scheme", Department of Communities and Local Government
- "Key Workers", City of London
- "Ask the expert: Key worker mortgages", BBC, 27 January 2005
- "Key Worker Qualifying Roles", Ashford Borough Council
- "CPA association". Retrieved 2009-06-29.
- "Effective care co-ordination in mental health services: modernising the care programme approach - A policy booklet". Retrieved 2009-06-29.