Best Dresses for Your 20s, 30s, 40s

For your entrée into the professional world, make it your goal to look appropriate while showcasing your feminine side. "Shirtdresses are never frumpy or matronly," says Alison Gary, editor-in-chief of Wardrobe Oxygen. A good one, like this turquoise, patterned style, skims your curves, nipping the waist but flaring out enough to avoid hugging the rear -- a no-no for daytime. Get extra mileage out of the dress by switching out the attached belt for a skinny cincher you already own.

Sheer Printed Shirtdress, $89.90, The Limited

"In college, you might have had sexy dresses to wear to sorority formals or to nights out," says Gary. "You need something that's a little more polished and sophisticated so you can wear it to a friend's wedding or your company holiday party." This number shows off toned arms and legs, and defines the waist, but is nonetheless conservative enough to wear in front of your potential in-laws or your company CEO. Both timeless and trendy, it will remain a wardrobe staple well into your 30s.

Princess Seam Dress, $59.95, Gap

Falling temperatures are no reason to wear pants every day. Stay warm, cozy, and stylish by slipping a roomy knit over tights and knee-high boots. A great way to transition into the cooler months, knits -- chunky and traditional, white and dark, graphic and solid -- were huge on the fall runways. But be forewarned: sweater dresses hug you everywhere, and aren't super-forgiving of bumps and lumps. Consider busting out shapewear to help with overall smoothing.

Knitted Cream Cable Sleeve Dress, $49, Dorothy Perkins

Once you have kids, curves appear in places they've never before existed. Embrace -- and flatter -- them in a wrap dress. Like a shirtdress, it transitions easily from day to night, and it feels good. Wrinkle-resistant, and mom-friendly, wrap dresses tend to have some stretch to them, making them ideal for crawling around hunting for lost toys, sitting in your office-chair all day long, and a cocktail party. "I lived in wrap dresses when my daughter was little," says Gary, who has a three-and-a-half year-old. "It looked work-appropriate, but it was easy for nursing and pumping."

Long-Sleeved Wrap Dress, $32.94, Old Navy

As stylish over tights and ballet flats as with bare legs and sandals, a simple shift is a must-have by time you hit 30. Whether you're meeting the hubby for happy hour, or looking for that just-dressy-enough look for a daytime wedding, this shape is a totally polished way to show off toned arms and legs. Up the "wow" factor by choosing one in a lively print. If the pattern on your dress is as exotic as things get, you've taken an admirable walk on the wild side.

Mod Zebra Textured Cotton Shift, $52.49, Loft

First of all, let's get over the idea that peplums add bulk. In fact, the extra fabric around the waistline actually hides imperfections around the lower belly, an area where most of us can use a helping hand. "In your 30s, peplum is a trend you can wear without it wearing you," says Gary. "It makes you stand out in a crowd." Although this dress may appear solid from far away, its subtle, lace-like pattern is another worthy extra. No need to save it for a special occasion -- this one's machine washable.

Jacquard Dress With a Peplum Front, $79.90, Zara

Thanks to the popularity of Mad Men -- which we watch equally for the plot and the fashion -- these retro-cut dresses are everywhere. Astonishing in their ability to make your waist seem tiny, these swingy numbers are also highly versatile. -- both in season and in purpose. "Wear with a scarf and pumps for the office, and switch to a statement necklace and heels for the evening," suggests Gary. For winter, simply add a cardigan and opaque tights.

Oasis Red Skater Dress, $86.23, Asos

This sophisticated style can look too mature on younger women, but once you hit your 40s, it's a perfect go-to. Less square than a shift, a sheath nips the waist -- even add a belt if you like -- and is touch more feminine. This ponté knit version is refined looking, but as comfortable as a pair of yoga pants. "You're still able to get down with your kids," promises Gary. "You're able to move with it. It doesn't wrinkle." Sold!

Sleeveless Ponté Sheath Dress with Pockets, $80, Land's End