Contractor G&J Seddon has been awarded a further £3.5m contract to build the new school for Junior Girls at Bolton School.
The new three-storey building will be built within the Bolton School campus on Chorley New Road and will sit on the site of the previous Infants' School, which has recently moved to its brand new premises also built by G&J Seddon.
Jonathan Seddon, managing director of G&J Seddon, said: "We work hard at establishing strong relationships with all of our customers. This contract demonstrates the high level of trust and understanding we have developed with Bolton School during our previous project."
Simon Marsden, school clerk and treasurer, said: "This is phase two of our £18m building programme and it represents the next very exciting stage in Bolton School's development as we seek to offer the very best in education for future generations from across the region."
The latest phase of construction will begin over the summer and is expected to take one year to complete. It is hoped that pupils will be able to move into their new school in the term beginning September 2010.