Mutuals approved a total of 24,295 loans in February, up 16% from the 21,020 in February 2012 and up from the 20,979 loans approved in January.
Gross mortgage lending by building societies and other mutual lenders was £2.5 billion in February, up by 29% compared to the same month last year.
Lending by mutuals increased 5% to a give them a 23% market share of gross lending in February.
Paul Broadhead, Head of Mortgage Policy, Building Societies Association, said: "Building societies and other mutual lenders continued to show their commitment to UK homebuyers in February. Both gross and net mortgage lending rose in a market where lending by other institutions remained weak.
“We welcome the Government’s renewed focus on the challenges faced by people looking to buy for the first time or move home, but it is a shame that the Help to Buy guarantee is needed.
“If all lenders acted to help first-time buyers and other creditworthy borrowers with smaller deposits, as mutuals have done consistently over the last year and more, this intervention would not be needed.
“Around one in three mortgages from BSA members are already to first-time buyers, many at higher loan to value ratios. The sector is in a strong position to lend in 2013.”