The prospect of free labor is tempting for any business, especially cash-strapped startups, but is offering only school credit the best way to go?

The labor department has six criteria for determining whether or not an employee at a for-profit business can be classified as an unpaid intern, including one provision that the employer gain no actual benefit from an unpaid intern. Obviously that defeats one of the main reasons a startup may want an intern.

Despite the legal gray area, productive unpaid positions are common. I actually had several unpaid internships (of the productive kind) before landing my first full time reporting job, and they largely worked as advertised. I learned many of the skills that I use in my day-to-day work, and I gained confidence in my own abilities. However, my time in internship limbo was painful. I knew my work was being undervalued, I still had rent and bills to pay, and of course I had to eat.

If I hadn’t been able to support myself through other means, I never would have been able to get that kind of training. For that reason, former newsroom recruiter Joe Grimm, now a professor at Michigan State, believes that unpaid internships put those without an alternate means of support at a disadvantage.

“Unpaid internships discriminate against people who do not come from affluent families,” he wrote to a colleague in an email he posted on his Poynter.org column.

These tough economic times are making free labor more and more common. So if you’re considering bringing in an intern, consider making the exchange beneficial for both parties. It will at least show them that you respect their time and work.