1. You value outside opinions and professional expertise. The people who work in ad agencies are professionals—like lawyers and plumbers and accountants. I’ve dabbled in all three of those areas enough to know that dealing with them is best left to professionals. I’ve also learned that sometimes I’m too close to a situation and I need outside advisors to help me sort out a plan of action.

Those are good reasons to hire an ad agency. It’s shocking how often we reveal strategic advantages and pitfalls our clients never anticipated—just because we have an outsider’s perspective. And because we’re professionals. You do what you do because you’re good at it. We’re good at advertising.

2. You have ongoing advertising/marketing needs that require professional attention. If you need a product flyer or a radio spot, you may not need an ad agency. If you need a coordinated campaign that includes several media, or you need a big collateral system, or ongoing content for your blog, or videos and programs and speeches for your big event, or—well, you get it. Ad agencies are great for planning, coordinating, and executing complicated marketing communications programs and helping you get the most for the money you spend.

3. You can’t afford to have top-level advertising talent on staff. We employ the talents of expert writers, designers, art directors, creative directors, web developers, business and marketing strategists, media planners, project managers, and account executives—not to mention photographers, videographers, directors, audio engineers, models and actors, printers, etc. All of these people have professional and technical expertise used in the creation of advertising.

You probably don’t want all these people on staff. (Neither do we.) If you’re a big company, you can probably afford to have some of them on the payroll, and you may be able to keep them busy enough to justify their salaries. And if you’re lucky, you can snag a great writer or a fabulous designer with the promise of a steady paycheck in a stable environment. We know lots of great creative people who work on the client side.

But most top ad people don’t want to work for in-house departments. Most want to work for ad agencies, where they can use their talents to work on a variety of challenging assignments for different clients in different industries. They’re motivated less by job security and more by the prospect of doing daring work.

Or they want to work for themselves. Which brings us to the next good reason…

4. You don’t want to spend all your time wrangling freelancers. 

You can get really good freelance marketing help for less than you’d pay an ad agency for the same work. Freelancers have lower overhead.

But hiring and coordinating freelancers can be a hassle. With an ad agency, you ideally have a single point of contact—an account executive—you can lean on to coordinate getting all your work done. Having a great account executive you can rely on to oversee your advertising business can save you countless hours you’d otherwise spend bringing together the right team for each part of the job and keeping your projects moving. Ask anyone who’s ever had one: a great AE is worth his or her weight in the paperwork you don’t have to do to coordinate your advertising efforts.

5. You want to do the best advertising you possibly can. If you think any advertising is good advertising, you may not need an ad agency. If you want to shake up your market and rocket your company to power, influence, and wealth—and you’re committed to expending the brainpower, time, and money to do the advertising it takes to help get you there—you probably need an ad agency.

All of which brings brings me back to my first thought: The reason you hire an ad agency is that we’re professionals. We’re really good at this stuff. When you invest the time and money in great advertising, it works.

You want your advertising to work? Hire a great ad agency and trust them. That’s why.