Jessica Simpson hopped off her flight from Mexico and jumped right back to work.

The pop star, who returned to Los Angeles yesterday after spending a few days unwinding (from what, we wonder) with her family south of the border, apparently isn't in the mood for more R&R.

She was on the move today, making a quick stop at a Marriott hotel in Sherman Oaks and then holing up in a West Hollywood recording studio.

A source close to the songstress told E! News that Simpson planned to spend six to eight hours at the studio working on material for a "country crossover" album.

Sounds about right for a little lady who's been suspiciously without her Cowboy for a while.