How to Dress for a Rehearsal Dinner
To decide what to wear to a rehearsal dinner, check the invitation to see what the dress code is. If it is a "black tie" event, men should wear a tuxedo, shirt, and tie, while women should wear a cocktail dress. Alternatively, a "semi formal" dinner indicates men should wear a suit and tie, while women could go for a skirt and dressy blouse. If you're still unsure what to wear, check the type of food being served at the dinner and its location to get an idea of the dress code. Finally, call the venue or hosts to confirm.
Check the invitation for dress details. The bride and groom or the groom's parents will have sent you an invitation noting the details of the rehearsal dinner. In addition to the time and date of the event, some invitations note the style of dress the hosts wish for guests to wear. Here are some of the different styles of dress you may see listed on a rehearsal dinner invitation: Black tie. This style is more common for the actual wedding day, but you may see a request for black tie attire on a rehearsal dinner invitation. Men should wear a tuxedo to a black tie event, while women should wear a cocktail dress or long evening gown. Formal or black tie optional. A formal or black tie optional event indicates that the suggested attire is slightly less formal than a black tie event. Men may wear a tuxedo, but could also wear a dark suit and tie. Women may wear a cocktail dress, dressy suit or evening gown. Dress for a "beach formal" event. If the invitation states that the rehearsal dinner is beach formal, be prepared for an elegant event held outdoors. Guests should dress for the elements, including sun and sand. Men may wear a lightweight suit with a linen shirt, or khaki or linen pants with a cotton button-down shirt. Ties typically are not required at beach formal events. Women may wear a tea-length or knee-length sundress. Select appropriate attire for a "semi-formal" or "dressy casual" rehearsal dinner. For men, semi-formal attire indicates a suit and tie. A dark suit is recommended for evening events, while lighter colors may be appropriate for a daytime event. However, as most rehearsal dinners are held in the evening, darker colors are recommended. Women may wear a cocktail dress or a dressy skirt and top to a semi-formal dinner. Dress for a "casual" event. While casual dress to some people may mean jeans and shorts, in most cases that is not appropriate attire for a rehearsal dinner unless specifically noted on the invitation. Men should wear dress pants with a polo or button-down shirt to a casual rehearsal dinner. Women should wear a dress, or skirt or pants with a dressy blouse. Note the time of the dinner. If the invitation doesn't state what type of attire to wear, there are other clues to examine. You can determine a lot about how to dress based on the time of day the dinner is taking place. If it's on the earlier side, say 5:00 pm, it's probably more of a happy hour or cocktail hour, which would imply less formal dress than a full dinner beginning at 7 or so. Some rehearsal meals are not dinners, but lunches or brunches. If this is the case, the attire will probably be slightly less formal. The time alone is not usually enough to give you a clear indication of what to wear, so take other factors into account along with this one. Note the location of the dinner. This is probably the most important factor to take into account when you're deciding what to wear. Fine restaurants may have a dress code, requiring men to wear jackets and ties, for example. More casual establishments won't have a dress code, and neither will most outdoor functions. In these cases you'll have to use your own discretion to figure out what's appropriate to wear. Consider the theme of the wedding. The wedding theme can indicate appropriate rehearsal dinner attire. In general, select rehearsal dinner attire similar to the wedding attire, except less elegant. For example, a beach wedding will likely have a relaxed atmosphere at the rehearsal dinner, which would suggest sundresses for women and slacks with polo shirts for men. A very traditional wedding might suggest classic semi-formal attire for the rehearsal dinner, such as suits for men and cocktail dresses for women. Determine the appropriate attire based on the rehearsal dinner menu. If specified on the invitation, the type of food served can indicate the formality of the event. For example, a clambake on the beach may suggest casual attire, while a five-course meal may suggest semi-formal attire. Call the venue or hosts if you still aren't sure. If you're worried there's a dress code and you aren't sure what it is, it's perfectly fine to call either the venue or the host to find out what will be appropriate. There's no need to go into great detail about what you intend to wear; just ask whether the event will be formal, semi-formal, or informal. After that, it's up to you to pick out the right outfit. Wear nice fabrics. Silk, chiffon, and fine knits are right for a formal or informal rehearsal dinner. Avoid wearing inexpensive cotton or polyester. Go for a fabric that looks tasteful and elegant, and make sure it isn't too sheer. Women can wear dresses made of most anything but denim or inexpensive polyester. Men should go for suits or tuxedos made of wool. If it's summertime, a lighter fabric is fine. Wear tasteful cuts. When you're dressing for a rehearsal dinner that's formal or semi-formal nature, go for tasteful, classic cuts that don't reveal too much or stand out from the crowd more than necessary. You don't want to upstage the bride and draw attention to yourself. Either floor-length or cocktail-length dresses are appropriate. Don't wear a dress too high above the knee. Men should stick with suits that are cut in a classic tuxedo style, paired with a white shirt and a black bow tie and cummerbund. Wear appropriate colors. The colors you wear should be in keeping with the season. Go for jewel tones and darker hues in the fall or winter, and pastels or bright colors during the spring and summer. Wear dress shoes. Women should wear high heels or dress flats that match their dresses, while men should wear leather dress shoes in black or dark brown. Avoid wearing sandals or casual pumps. Men should shine their shoes if they are scuffed. Wear weather-appropriate clothing. Many informal rehearsal dinners take place in an outdoor setting. Be sure to bring a sweater or jacket that matches your nice dress or suit so you'll still look appropriate even when you add a layer to your outfit. Don't upstage yourself. Since you'll be going to the wedding the next day, you don't want to wear something fancier than your wedding day attire. Save your most formal, prettiest dress for the day of the wedding, and wear something more understated to the rehearsal dinner. When in doubt, go for business casual. If the event doesn't specify that it's "black tie," but you'd still like to wear something on the fancier side, business casual is usually fine. Gray, navy, black, or dark red business-style dresses or pantsuits are appropriate for most rehearsal dinners. For men, suit pants, a jacket and tie of the sort you would wear to a business meeting will usually fit in well. 
Check the invitation for dress details. Note the time of the dinner. Note the location of the dinner. Consider the theme of the wedding. Determine the appropriate attire based on the rehearsal dinner menu. Call the venue or hosts if you still aren't sure. Wear nice fabrics. Wear tasteful cuts. Wear appropriate colors. Wear dress shoes. Wear weather-appropriate clothing. Don't upstage yourself. When in doubt, go for business casual. 