The invitation to the 50th birthday celebration arrives, and you eagerly scan down the invite to find the date, time and location. But, then you stumble over "Semi-casual attire." While you're familiar with casual, semi-formal, formal and black tie attire, you may wonder exactly what semi-casual means when dressing for a party.

A step above casual, but not as dressy as semi-formal, semi-casual attire generally means slacks, a nice shirt or blouse, a skirt and blouse set or a nice dress. It does not include jeans, shorts, athletic wear, T-shirts, sundresses, flip-flops or sweats. Keep jewelry simple and low-key; semi-casual doesn't include bling. While there are exceptions to every rule, when in doubt, especially for a 50th birthday celebration, it's better to slightly overdress than to show up in a designer jeans outfit and find everyone else wearing silk dresses or slacks and blazers.

A warm summer day allows the ladies to choose lighter garb, including sandals, slacks in pastel colors with a matching blouse or lightweight sweater, a knee-length dress with or without sleeves and a light jacket in case the weather turns cool. The men may choose a "Miami Vice" look, with white or tan slacks and loose blazer, a designer T-shirt in a pastel color and loafers. Alternately, a man might choose slacks paired with a tone-on-tone Hawaiian-style shirt and leather sandals.

Cold winter weather encourages heavier clothing, including slacks paired with a button down shirt and a sweater for the men and sweater dresses with leggings and ankle boots for the ladies. Ladies may also choose slacks and a sweater or blouse. Men might wear a dark slacks and blazer outfit with a turtleneck instead of a T-shirt or a button-down shirt under a warm sweater. A warm winter coat, gloves and hat keep men and women warm on the way to and from the party.

For an evening 50th birthday party, step up the attire to a dressier look. A lady might wear a jersey dress in a simple style with understated jewelry, such as a single pendant or string of pearls. Other dress or slacks outfits might dress up nicely with a scarf or head wrap. While not necessary, men may choose to add a tie to a slacks and blazer outfit. Dark, rich jewel tones are always appropriate for evening wear, whether a semi-casual party or a more formal affair.