Star Tracks: Tuedsay, December 22, 2009

01 of 14

GETTING WARM

Pile on the layers! Mary-Kate Olsen braces herself against the winter chill, hugging a warm drink to her body after leaving her New York City apartment Monday.

02 of 14

OH BABY!

How I Met Your Mother star Alyson Hannigan totes 9-month-old daughter Satyana – and uses her stroller as a shopping cart! – while out in Santa Monica, Calif., Monday.

03 of 14

SMOKE & MIRRORS

Who's ready for the disco? The ever-fashionable Lady Gaga brings her high style and Monster Ball tour to L.A.'s Nokia Theatre for a glitzy performance Monday night. The singer, who will play two more shows in Los Angeles, wraps the U.S. leg of the tour in New York next month.

04 of 14

WELL 'RED'

What a gentleman! Mariah Carey gets a helping hand from her color-coordinated hubby Nick Cannon while continuing their winter getaway in Aspen, Colo., Monday.

05 of 14

GETTING SCHOOLED

Christina Aguilera and husband Jordan Bratman enjoy each other's company while reportedly scoping out potential schools for 2-year-old son Max Monday in West Hollywood, Calif.

06 of 14

COFFEE CLUTCH

Reese Witherspoon is serious about her coffee! The actress steps out for a little caffeine and conversation with a friend in Brentwood, Calif., Monday.

07 of 14

HIGH WATTAGE

Now that's how to dress for the grocery store! Dita Von Teese keeps it glam while picking up food at Gelson's in L.A. Monday.

08 of 14

COOL & COLLECTED

There's nothing frosty about her attitude! Jessica Simpson hits the New York City streets Monday in a fur-lined jacket and snow boots reportedly to meet up with sister Ashlee – who's starring on Broadway in Chicago.

09 of 14

'SNEAK' PEAK

Vanessa Hudgens gets a kick out of her vibrant sneakers during an autograph signing at the Skechers store in Universal City, Calif., Sunday. The actress was promoting her partnership with the shoe company's Ecko Red line.

10 of 14

AT PLAY

Victoria Beckham shows off her gams and one serious fur after catching the musical Jersey Boys at London's Prince Edward Theatre Monday with husband David Beckham (not pictured) and their three boys.

11 of 14

CROPPING UP

After festively sightseeing with her sons, Gwen Stefani reveals yet another seasonally chic look – check out her layered trench coat – Sunday during a solo outing in London.

12 of 14

LEAN ON ME

What a stylish pair! Katy Perry and boyfriend Russell Brand stick together Monday while shopping in East London.

13 of 14

CARRIED AWAY

Way to multi-task! Renée Zellweger works her phone and balances a tray of hot beverages after making a Starbucks run Monday in Brentwood, Calif.

14 of 14

CAN DO

Meanwhile, boyfriend Bradley Cooper is on domestic duty: The actor checks a few chores off his to-do list, setting up garbage cans outside his Los Angeles home Monday.