Casual Fridays are days in which the usual dress code of an office is relaxed. Since Fridays mark the start of the weekend in many countries, behavior in general tends to be more relaxed on Fridays, with some employers not being as picky about standards, and sometimes this is formalized in a casual Friday policy. As anyone who has worked in an office with casual Fridays knows, the term is a bit of a misnomer, because truly casual clothing like sweatpants and t-shirts is usually frowned upon.

The casual Friday concept was one of the first signs that rigorous dress codes for offices were starting to relax. The principle of Dress-Down Fridays appears to have emerged around the 1950s, probably in response to changing attitudes about careers and the workplace. Over time, some offices have relaxed their dress codes even more, adopting a business casual dress code every day.

On casual Fridays, employees may wear clothing which is classified as “business casual,” meaning that it still adheres to certain standards. Clothing must be clean and in good repair, with no stains or discolorations. Men are generally allowed to wear slacks and blazers, and in some offices they may be allowed to wear button down shirts or polo shirts, with or without a tie. Women tend to wear neat skirts or dresses; slacks are common and generally perfectly acceptable, except in very conservative workplaces.

As a general rule, extremely casual clothing like jeans, shorts, t-shirts, tank tops, and so forth is discouraged on casual Fridays. Employees are still expected to make an effort to look professional, out of respect to their offices and their clients. Since some clients prefer a more formal look, some employees like to keep dressy coats and ties in their offices on casual Fridays, in case they need to dress up for a client.

Many people feel that casual Fridays are good for employee morale, encouraging employees to express their individuality and feel more comfortable in the office. Others feel that business casual dress and the concept of casual Fridays devalues the workplace, by taking a sense of formality and respect away. Approaches to casual Fridays vary, depending on the industry and the nation; the technology industry, for example, is well known for casual dress in general, while major financial companies tend to frown on casual dress.