Nicole Richie by Lester Cohen/WireImage.com
Nicole Richie, 25, pleaded guilty to driving under the influence this morning and was sentenced to serve 96 hours in jail.

Richie was credited for six hours of time served for her post arrest jail
stint, meaning she'll actually serve 90 hours, says Jane Robison, spokeswoman for the Los Angeles District Attorney's office.

Richie was fined $2,048 and ordered to undertake 21 days of an alcohol education course. She must complete her 90 hours by September 28.

The Simple Life star was arrested December 11 after police say she drove the wrong way on a California highway. Robison also says Richie was given three years probation and "was admonished
by the judge that she must stay clean and cannot be arrested for any other offense. If she violates probation in any way, she'll face more jail, and that will be up to a year." This was Richie's second DUI conviction.

It has not been determined whether she will serve her sentence in the Los Angeles County or City jail. "We expect she won't go to county, she'll go to
some city facility," says Robison. But that could only happen if there's space. City jail, which inmates pay for themselves, is considered less severe than the county facility. "If you can afford it," most people, confirms Robison, "will opt for a city jail," even though "she will have to serve her full time because they don't have the overcrowding issue that County does." Overcrowding often allows for an early release.

Richie, who is rumored to be pregnant, entered the Glendale, Calif. courthouse holding the arm of her boyfriend, musician Joel Madden. Executives at E! Entertainment, which produces The Simple Life, would not comment on the sentencing, but did tell TV Guide that "no decisions have been made" regarding the series' renewal. - Reporting by N.F. Mendoza