Many businesses allow somewhat casual attire at least once a week, but dress codes vary. Here are some guidelines for dressing business casual, which is a notch below business formal. Let comfort and professionalism guide you when you're dressing for business casual occasions. Also, check out our Pinterest page for visual examples!

• Ask your internship supervisor for official guidelines. Business casual means different things at different companies. At a large corporation, it may mean a sport coat with a tie; at a smaller company, it may mean khakis and a polo shirt.
• Before you go casual, check your daily planner to make sure you do not have any meetings that require formal business attire.
• Select clean, pressed and wrinkle-free clothes. Your outfit should communicate professionalism.
• Wear a collared shirt with an undershirt. You can break up the oxford shirt monotony by wearing a linen or flannel shirt or one with a band collar.
• Knitted shirts and polo shirts are also generally acceptable. A casual sport coat is appropriate.
• Wear khakis, chinos, corduroys or other non-denim slacks. Check your company's policy before you decide to wear jeans to work.
• Be sure to wear a belt, and have it match the color of your shoes.
• Wear socks that match the color of your pants - leave white socks or tube socks in your gym bag.
• Washington, D.C. has a highly professional atmosphere. Please be aware that within a conservative workplace, colorful hair, colorful clothing, piercings, tattoos, and other styles of identity presentation may be viewed as atypical. 
• Limit visible body piercings to your ears. When possible, cover any tattoos or other forms of body art with clothing.
• Choose oxfords, loafers, or rubber-soled leather shoes or boots for a casual day. Wingtips are often too formal. Worn-out shoes, sandals, or athletic shoes do not make the grade.

Tips:

• If your company has no written guidelines, observe what others are wearing to get an idea of what is acceptable.
• Your casual-day outfit should be formal enough that you can throw on a sport coat and meet a client.