"There is little doubt the environment at the club has changed significantly since David has taken over," said chief executive David Smith.
Ripley played for the club from 1984 to 2001, scoring more than 10,000 runs and taking over 900 catches in all forms of the game as wicketkeeper.
He still holds two of the club's partnership records, having shared a fifth-wicket stand of 401 against Glamorgan with Mal Loye in 1998 and added 293 for the seventh wicket with David Sales the following year.
Following his retirement, he was put in charge of the youth set-up and second XI at Wantage Road and has now progressed to the first-team role.
"A good dressing room is important for player retention and new player recruitment, as is a sense of belonging and what the club stands for.
"David has impressed everyone in how he has handled all elements of the job since taking over in early July," Smith added.
Northants are currently fifth in County Championship Division Two but have won only two out of 19 games in limited overs cricket so far this summer - albeit six of them ended in n-results because of the weather.
"The club recognises the need to improve its white ball one-day cricket performances which have fallen below both the club and its supporters' expectations during 2012 and we are actively looking to recruit players to assist us in this important area of the game," a club statement said.
Phil Rowe has. meanwhile, been named as the new second XI coach and academy director.
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