Business casual attire
Business casual attire will be appropriate to wear at some career fairs — attire should be specified on the website or other promotional materials for each fair. Note that some fairs suggest or require interview attire. Do your research in advance.
Most employer information sessions. These are typically evening sessions held the day prior to an employer's first interview day on campus. Information sessions held in a classroom on campus or conducted as a presentation to a large group don't require you to be quite as strict in your attire as a reception-type event. Some employer information sessions are conducted as receptions on- or off-campus, perhaps in a hotel facility. In some cases interview attire, or business attire which is more formal than business casual, may be called for. This can depend on the industry and the type of employer hosting the event. If you are in doubt, ask the employer before attending.
The invitation, flyer or notice says to. A no-brainer!
When in doubt, ask the host or sponsor about attire for a function you will be attending. It is never wrong to politely inquire about appropriate attire.
Business casual is crisp, neat, and should look appropriate even for a chance meeting with a CEO. It should not look like cocktail or party or picnic attire. Avoid tight or baggy clothing; business casual is classic rather than trendy.
Basics
Khaki or dark pants, neatly pressed, and a pressed long-sleeved, buttoned solid shirt are safe for both men and women. Women can wear sweaters; cleavage is not business-appropriate (despite what you see in the media). Polo/golf shirts, unwrinkled, are appropriate if you know the environment will be quite casual, outdoors or in a very hot location. This may not seem like terribly exciting attire, but you are not trying to stand out for your cutting edge look, but for your good judgment in a business environment.
Shoes and belt
Wear a leather belt and leather shoes. Athletic shoes are inappropriate.
Cost and quality
You are not expected to be able to afford the same clothing as a corporate CEO. However, do invest in quality that will look appropriate during your first two or three years on the job for a business casual environment or occasions.
Details
Everything should be clean, well pressed, and not show wear. Even the nicest khakis after 100 washings may not be your best choice for a reception. Carefully inspect new clothes for tags, and all clothes for dangling threads, etc. (as with interview attire).
Use common sense
If there are six inches of snow on the ground and/or you are rushing to get to an information session between classes and you left home 12 hours earlier, no one will expect you to show up looking ready for a photo shoot — they'll just be happy you made it! Just avoid wearing gym clothes and jeans. If you show up at an event and realize you're not as well dressed as you should be, make a quick, pleasant apology and make a good impression with your interpersonal skills and intelligent questions.
Ties
Ties are generally not necessary for business casual, but if you are in doubt, you can wear a tie. It never hurts to slightly overdress; by dressing nicely, you pay a compliment to your host. You can always wear the tie and discreetly walk by the room where the function is held; if no one else is wearing a tie, you can discreetly remove yours. (Then put it in your book bag or other discreet place. Don't stuff it in your pocket and let part of it hang out.)
Shirts
Long-sleeved shirts are considered dressier than short-sleeved and are appropriate even in summer. Choosing white or light blue solid, or conservative stripes is your safest bet. Polo shirts (tucked in, of course) are acceptable in more casual situations.
Socks
Wear dark socks, mid-calf length so no skin is visible when you sit down.
Shoes
Leather shoes should be worn. No sandals, athletic shoes or hiking boots.
Facial hair
Just as with interviews: Facial hair, if worn, should be well-groomed. Know your industry and how conservative it is; observe men in your industry if you are unsure what's appropriate or are considering changing your look.
Jewelry
Wear a conservative watch. If you choose to wear other jewelry, be conservative. Removing earrings is safest. For conservative industries, don't wear earrings. Observe other men in your industry to see what is acceptable.
Watches/cell phones/checking the time
If you use your cell phone as a watch, just be careful that you don't look like you're taking calls/texts while speaking with employers. Your attention should be directed on the people with whom you are physically present. Be discreet when checking time; frequent checking sends the message that you are bored.
Be careful non to confuse club attire with business attire. If you would wear it to a club, you probably shouldn't wear it in a business environment. Also, much of the attire shown in media is not appropriate for business environments, so be cautious as you look for examples. Feel free to talk with a career advisor if you have questions.
Pants or skirts
Women can wear casual pants or skirts. Neither should be tight. Fabrics should be crisp; colors should generally be solid; navy, black, gray, brown and khaki are always safe bets. For the most business-like appearance, pants should be creased and tailored; neither extreme of tight or flowing. If you are pursuing a conservative industry and are in doubt, observe well-dressed women in your industry on the job, at career fairs, at information sessions, etc.
Skirt length and slits
Your skirt should come at least to your knees while you are standing. While you are seated, your thighs should be covered. If your skirt comes to just below the knee, a slit to just above the knee might be acceptable. A very long skirt should not be slit to above the knee. Generally slits in the center back of a skirt — to facilitate walking a stair climbing — are acceptable. Slits to facilitate a view of your legs are not appropriate for business purposes. Slips should not be visible.
Shirt and sweaters
In addition to tailored shirts or blouses, tailored knit sweaters and sweater sets are appropriate business casual choices for women. Cotton, silk, and blends are appropriate. Velvets and shimmery fabrics suitable for parties are not appropriate. Fit should not be tight. Cleavage is not appropriate to business and job search occasions.
Jewelry and accessories
Wear a conservative watch. Jewelry and scarf styles come and go. Keep your choices simple and leaning toward conservative. Avoid extremes of style and color. If your industry is creative, you may have more flexibility than someone pursuing a conservative industry.
Cosmetics
Keep makeup conservative and natural looking. A little is usually better than none for a polished look. Nails should be clean and well groomed. Avoid extremes of nail length and polish color, especially in conservative industries.
Shoes
Should be leather or fabric / microfiber. Appropriate colors are black, navy, brown, tan, taupe (to coordinate with your other attire and accessories); white and pastels are not appropriate. For the most conservative look, toes should be covered. Sandals which are neither extremely dressy nor extremely casual might be appropriate. Thin straps and spike heels are not appropriate. Chunky heels and platforms are not appropriate. Your choices reflect your judgment. Make certain you can walk comfortably in your shoes; hobbling around a job fair in shoes that are pinching your feet does not convey a professional image and does not convey good judgment.
Hose
Not essential for business casual, but are recommended if your skirt is knee length (rather than calf length) and in more formal environments such as hotels. Climate and weather can be a factor. Hose may not be expected in hot climates/weather and in less conservative industries. Hose may be expected in more conservative industries. All your choices send a message about your judgment; if the weather is extremely cold/snowy/icy, and you wear a skirt with bare legs, you won't look like you have good judgment.
Purse or bag
If you carry a purse, keep it simple, or carry a small briefcase or business-like tote bag in place of a purse. A structured bag tends to look more professional than something soft or floppy. Purse/bag color should coordinate with your shoes. A briefcase is certainly not necessary for most business casual events. Leather, microfiber and fine wovens are appropriate. Casual canvas and straw are not appropriate.
Hair
Should be clean and neat.
Shoes
Should be in polished condition. Make sure heels are not worn.
Details
No missing buttons, no lint; and don’t forget to remove external tags and tacking stitches from new clothes.
Hands
Clean fingernails.
Fit
Clothes should be clean, neatly pressed, and fit properly, neither tight nor baggy.
Smell
Perfume or cologne should be used sparingly or not at all.
No odors on clothes.
Don't smell like smoke.
Padfolios
Preferred over a bulky briefcase. A small briefcase is also appropriate, but if you have no reason to carry a briefcase, don't; you risk looking silly.
Book bags / backpacks / totes you carry on campus
Appropriate to carry to an information session held on campus, depending in time and location and the employer's instructions about attire (after all, you are a student). For career fairs and job fairs on campus, bulky backpacks are sometimes checked at the door (it's too crowded for people to be bumping into others with backpacks), and you should carry a padfolio only. Consider the industry and type of event in choosing what to carry.
It's preferable not to carry a backpack to an event held at a hotel.