Chris Rogers has quit as Derbyshire captain and will be replaced by Greg Smith for the rest of the 2010 season.
The Australian batsman has captained the county since 2008 but decided to make way for Smith, who led the team in this season's Friends Provident t20 competition.
"I have thoroughly enjoyed my time as captain of Derbyshire County Cricket Club and there have been some fantastic moments along the way," said Rogers.
"Although I had every intention of captaining the team until the end of the season, both (head of cricket) John Morris and I believe it is in the best interests of the club to give Greg this opportunity.
"I will help him in any way that I can and will continue to act as a senior player and mentor for the younger players in our side as well as continuing to do my best for the team as a batsman."
Morris said: "Chris has done a great job as captain of the team for the past two years and I thank him for his efforts and dedication to the role.
"Having been vice-captain throughout the current season and experienced the captaincy during the Friends Provident t20 campaign, it is a natural progression that Greg now takes over as captain."
Derbyshire are currently bottom of Division Two of the LV County Championship and have not won in the four-day format since April.