1918–1950 • The Municipal Borough of Hemel Hempstead; • The Urban Districts of Berkhamsted, Harpenden, and Tring; • The Rural Districts of Berkhamsted and Hemel Hempstead; • The Rural District of St Albans parishes of Harpenden Rural, Redbourn, and Wheathampstead; and • The Rural District of Watford parishes of Abbots Langley and Sarratt.
1950–1974 • The Municipal Borough of Hemel Hempstead • The Urban Districts of Berkhamsted, Harpenden, and Tring; • The Rural Districts of Berkhamsted and Hemel Hempstead; and • The Rural District of St Albans parishes of Harpenden Rural and Redbourn.
Wheathampstead was transferred back to St Albans. Abbots Langley and Sarratt now included in the new constituency of South West Hertfordshire. 1974–1983 • The Municipal Borough of Hemel Hempstead; • The Urban Districts of Berkhamsted and Tring; and • The Rural Districts of Berkhamsted and Hemel Hempstead.
Harpenden and the part of the parishes of Harpenden Rural and Redbourn were transferred back to St Albans. The constituency was abolished for the
1983 general election. Berkhamsted and the area to the south of Hemel Hempstead, including
Kings Langley, was transferred to South West Hertfordshire. The remainder, including Hemel Hempstead and Tring, formed the new constituency of
West Hertfordshire.
1997–2010 • The District of Dacorum wards of Adeyfield East, Adeyfield West, Ashridge, Bennetts End, Boxmoor, Central, Chaulden, Crabtree, Cupid Green, Flamstead and Markyate, Gadebridge, Grove Hill, Highfield, Kings Langley, Leverstock Green, Nash Mills, South, and Warners End.
Re-established for the 1997 general election from the bulk of the abolished County Constituency of West Hertfordshire (excluding Tring). Kings Langley transferred back from South West Hertfordshire. 2010–2024 • The District of Dacorum wards of Adeyfield East, Adeyfield West, Apsley, Ashridge, Bennetts End, Boxmoor, Chaulden and Shrubhill, Corner Hall, Gadebridge, Grove Hill, Hemel Hempstead Central, Highfield and St Paul's, Kings Langley, Leverstock Green, Nash Mills, Warners End, Watling, and Woodhall.
Minor loss to South West Hertfordshire following revision of local authority wards. Current Further to the
2023 review of Westminster constituencies, which came into effect for the
2024 general election, the composition of the constituency is as follows (as they existed on 1 December 2020): • The District of Dacorum wards of: Adeyfield East; Adeyfield West; Apsley and Corner Hall; Bennetts End; Bovingdon, Flaunden and Chipperfield; Boxmoor; Chaulden and Warners End; Gadebridge; Grovehill; Hemel Hempstead Town; Highfield; Leverstock Green; Nash Mills; Woodhall Farm.
Moderate changes, with Kings Langley being transferred to South West Hertfordshire, in exchange for the rural Bovingdon, Flaunden and Chipperfield ward. The rural Ashridge and Watling wards to the north were moved to the newly created seat of Harpenden and Berkhamsted. == Members of Parliament ==