Lacey Green is a village and civil parish in Wycombe district near Princes Risborough, in Buckinghamshire, England. It is in the Chiltern Hills above the town.
The hamlet was known as Leasy Green in the early 19th century. It is twinned with Hambye in France.
Dated to 1650 by leading authority Stanley Freese, Lacey Green windmill is the oldest surviving smock mill in England and was restored from a state of almost total collapse by volunteers under the auspices of the Chiltern Society.
The Chilterns cover an area of 833 km2 (322 sq mi). They are 18 km (11 mi) wide at their widest, and stretch 74 km (46 mi) in a south west to north east diagonal from Goring-on-Thames in Oxfordshire, through Buckinghamshire, via Dunstable Downs and Deacon Hill in Bedfordshire, to near Hitchin in Hertfordshire.
The boundary of the hills is clearly defined on the north west side by the scarp slope. The dip slope is by definition more gradual, and merges with the landscape to the south east. The Thames is a clear end point to the south west, whereas north east of Luton the hills decline slowly in prominence.