Trends may come and go, but these dresses will always be a mainstay in our closets. Sure, we may gravitate toward different styles depending on the season  and "what's in," but if you stick to these eight essential silhouettes, you'll never be without the right look for any occasion — and we've thought of them all.
From a formal dress (yes, we all need one!) to a work standby, you'll be the girl who has it all just by having these few pieces. Scroll on to see what to shop and why it's worth it.
The Work Sheath
Even if your office doesn't have a "dress code" in place, you'll be happy you have a polished sheath dress in your closet for everything from interviews to a big presentation at work. Choose one like this J.Crew structured knit sheath  ($168) that's easy to change up with a jacket, jewelry, and your footwear of choice.
For the days when jeans just won't do, the maxi dress  ($80) is a perfect alternative. It's comfortable to travel in, it's easy to layer up, and it works all year. Long story short, it's a must.
The Day Dress
There are days when your jeans and t-shirts just won't cut it; that's when a perfect day dress like this Tibi denim dress  ($365) comes into play. You won't feel overdressed if you wear it to brunch with friends, and you'll certainly feel more polished for dinners out. It's not a special-occasion dress, but it's an elevated alternative to your basics that you'll rely on weekly, if not daily.
The Sweater Dress
When the weather starts to cool, you'll be happy you have a go-to sweater dress  ($345) in your arsenal to wear with boots and tights all Fall and Winter. It's a perfect layering piece.
The Formal Dress
For wedding  season, formal dinners, and special events, it becomes pretty essential to have an appropriate dress. That means something formal and full length, like this Elizabeth and James gown  ($695). Opt for one in a color or print that flatters your complexion and can be reinvented each time you wear it just by switching out the accessories.
It just doesn't feel like Spring and Summer without the perfect sundress. Find one that flatters your frame or shows off your best assets, like this Mara Hoffman dress  ($286), and wear it with flats or heels all season.
The Cocktail Dress
For those special occasions that don't call for a totally formal dress, you need a great cocktail dress  ($218) that can go from dinner and drinks to a party, if need be. Choose one with details that will work all year to get the most for your money.
Every woman's closet should come equipped with this staple  ($298). It's an iteration you can dress up or down and wear to both celebratory and somber occasions.
Get more of the essentials with these guides:
- The Tops Everyone Should Have in Her Closet 
- The 11 Things Every 20-Something Should Have in Her Wardrobe 
- Attention 30-Somethings, This Is Your Wardrobe Checklist