Let's face it: People who work at start-ups are an unusual breed. We love jumping head-first into problems that we have no clue how to solve, we become more energized the longer we go without sleep (thanks Breathable Energy!), and perhaps the most unusual of all, we have this crazy drive to change the world.

These elements, coupled with the risk of joining a start-up, makes finding quality employees pretty difficult. But I think we've done a particularly good job at Scvngr and LevelUp, and I think a lot of this is due to the fact that we've identified four key qualities that are essential for the start-up world, and four fail-proof ways to test for them during the interview process.

So, here it is. All of our secrets revealed. The four qualities, why they're important (I've elicited some help from my team for that part), and how to test for them.

1. Adaptability

Why it's important:

"No start-up, regardless of its stage, can survive without a dedicated respect to adaptability. Here at Scvngr, I started in the fall of 2010 as an Account Manger on the Rewards team. By the spring I was traveling the country, executing events for the Experiential Promotions team. It's that type of dynamic change, and the ability of Scvngr and LevelUp's employees to refocus their strengths effortlessly, which allows us to be leaders in our market spaces."
—Kyle Sherin, Director of Promotions

How to test for it:

If parachuting candidates onto a remote island populated with wolverines isn't your style, there's another tried-and-true test of adaptability that we're quite fond of: ask where they want to be in five years. While most job recruiters look for candidates who know exactly where they want to be, we're the opposite. If you're on a mission to work towards a certain job description, the start-up world isn't for you. Things change at start-ups all the time, so flexibility is much more important than having specific goals.

2. Honesty

Why it's important:

"At LevelUp, honesty is one of the things that keeps our team so efficient. Everyone acknowledges their own limitations and is honest about their capabilities, which allows us to dynamically adjust to changing circumstances and rebalance the load to address team members' strengths and weaknesses to be as effective as possible."
—Brendan Quinn, Zen Master

How to test for it:

Thanks to the Employee Polygraph Protection Act, our first choice for this test was, well...illegal. So we came up with a less cool but probably more accurate way to find out if interview candidates are honest: we ask them if they're nervous. If we ask someone whether they're nervous and they say no, but they're sweating, shaking, and breaking out in rashes, it's pretty much a red flag they're not being genuine.

3. Confidence

How it's important:

"Confidence brings versatility. Scvngr & LevelUp team members are frequently called upon to step into new roles and take on new responsibilities. Due to the confidence we have in ourselves and the confidence we have in one another, these transitions are positive, exciting and wildly productive."
—Christina Dorobek, VP, West Coast

How to test for it:

One of the best ways to test for confidence is to challenge something a candidate says during the interview. Say, for example, a candidate says they think the start-up down the street is building something awesome. Then I say, "that start-up is the worst idea since pink Vitamin Water. And that stuff tastes like Robitussin." What do they do? The most confident and qualified people will be able to defend themselves without wetting their pants or getting super aggressive.

4. Enthusiasm

Why it's important:

"If you can't get excited about your product and the people you work with, quit now. Most start-ups stock a truckload of Kool-Aid in the fridge, and you need an IV of the stuff to successfully navigate the roller coaster ride. Enthusiasm and optimism, combined with a laser focus and hard work, strongly correlate with success in start-up land."
—John Valentine, VP, East Coast

How to test for it:

If you don't have an acute sense for BS, then this is a must-have test for finding out whether someone is really as enthusiastic about working at your company as they appear: Get them to prove it. No, I'm not suggesting you haze your candidates (turns out that's illegal, too), but I am suggesting that you really drill them on why they want to work there. Making sure that they're not more enthusiastic about the idea of working at your company (free food, crazy team outings) than the reality of the job (disruptive ideas, talented co-workers) is super important.

What qualities do you think are essential for start-up land? Do you have any interesting ways of testing for them? Share your secrets in the comments section below!