Work will cover masterplanning and development for the area at Heartlands at Whitburn near the M8 between Edinburgh and Glasgow.
Phase one includes 2,000 homes and associated community infrastructure. A further 3,000 could be constructed under future phases.
Crest Nicholson has retained 30 per cent of the site for its own residential development.
Work is set to be underway by spring 2007 and run over 15 years.
Joint venture partners - who include the Royal Bank of Scotland - will be responsible for developing a 100 acre business park and two championship golf courses.