Dress codes tend to relax in the summer months. It’s difficult to endure business-formal when it’s 85 degrees.

But it’s equally difficult to maintain an aura of authority when you’re wearing a hot-pink golf shirt. When executives drop blazers, ties, and dress shoes, they are eliminating important clues to rank and power. The elements of a fully suited ensemble are designed to create a look of command.

So how to exude power-suit attitude in a summer-casual environment? Sticking to business formal often isn’t an option these days.

Eric Berg, a 31-year-old attorney in Washington, D.C., prefers suits for work, but says if he wore them every day, “People would be like, ‘who does this guy think he is?’ ” He compromises by wearing linen pants and sport jackets with driving shoes on summer Fridays.

With few clear rules—corporate dress rules can be so vague—people often reach for their weekend clothes during the summer, and then dress them up a notch. Skin-baring designs and lighter fabrics can reveal chest hair, lingerie straps and generally more than anyone needs to see across your desk. Such looks can be memorable: My office mates are still discussing the summer intern who wore a strapless sundress to work five years ago.

An effective approach is to begin with the office in mind. Rather than looking to the weekend portion of your closet, start with traditional work wear in summer fabrics. You can then dial down the dressiness or style it up for summer.

Yuta Powell, owner of the eponymous Madison Avenue boutique in New York, sometimes slings a rustic belt over a conservative dress, toning down the look ever so slightly. Also, she advises that women wear statement jewelry by artists, rather than the standard power earrings. Some of her favorites come from a Paris gallery called Ibu in the Palais Royal.

Summer is a terrific time to wear bright colors, as well as patterns from florals to argyle. Don’t be fearful, but do be tasteful. Think seasonal touches and small accents, not head-to-toe garden-party attire. Color standards differ regionally. A primary-color button-down shirt might work in the Midwest but not in New York. And with patterns, a little goes a long way. Ms. Powell has the sleeve linings of some blazers replaced with brightly patterned silk that looks simultaneously elegant and relaxed when the sleeves are folded back.

Tom Kalenderian, executive vice president for menswear at Barneys New York, recommends that men start with a good sport jacket, paired with a colorful shirt (he suggests Etro, a brand known for its swirly, often brilliantly colored prints) and cotton trousers from a quality maker such as Incotex or Zegna. “Be comfortable, but keep it sophisticated,” he says. It’s not necessary to buy luxury clothes—but it is smart to choose quality fabrics and construction that will hold up to wear.

It’s possible to dispense with the jacket in some offices. George DeMarco, a 47-year-old consumer-lending risk manager in Morristown, N.J., says he wears wool slacks and a pressed shirt with lace-up shoes on casual days. “You could look at it as wearing one half of a suit—the bottom half, without the tie and jacket,” he says.

But keep some of the elements of formal dress, such as collars, which project authority, whether they’re on a jacket, a shirt or a dress. And don’t dispense with socks (for men), undershirts under thin men’s shirts, and high-quality leather belts and shoes. Summer is no reason to wear your first miniskirt to work.

Equally important: Watch out for summer fabrics that wrinkle badly. Cotton and linen are often the culprits here, but there are linens and treated cottons that hold up nicely. Generally, the higher the quality, the better. Before buying apparel, test the fabric in the store by taking a fistful and squeezing. If it wrinkles dramatically, leave it on the rack.

Of course, every office is different, and creatives at an ad agency can show more whimsy than an accountant. But remember, the whole point of dressing for the office: It’s to hide our faults in the armor of strong clothing and put our best façade forward. We’re not at work to reveal our vulnerable parts.

Which brings us to shorts. The fashion industry hasn’t helped women lately with the all-out push to sell us shorts for the office. For stores, this is a way to sell a whole new clothing category—shorts suits—when shoppers are balking at buying more pairs of pants.

But shorts convey leisure. Even with a matching blazer, the primary thought they’re likely to trigger is not, “What a smart lawyer,” but rather, “Is she wearing shorts?”

Unless you work in the fashion industry, shorts could short-circuit your presentation to the board—even if they were excellently tailored by Carolina Herrera. Charla Krupp, author of the practically minded style books “How Not to Look Old” and “How To Never Look Fat Again,” takes a dim view of shorts in the office. “I think those shorts suits for work are insane,” she says. “It isn’t professional.” Her general rule of thumb: “If you can wear it to the beach, don’t wear it to the office.”

Even those who work in very casual offices often need to project authority. Steven Holben, who runs Holben Building Corp. in Denver, wears colorful sweaters and other clothes that are casual but nonetheless subtly convey quality. He calls his highly constructed St. Croix sweaters and strong-toed Johnston & Murphy shoes his “power attire,” because the quality of the manufacturing is recognizable. He wears a vintage IWC watch for important meetings.

The people he wants to do business with “will recognize the shoes,” says Mr. Holben. “It makes a difference in the way people perceive me.”