It’s well known in admissions circles that campus tours are strongly tied to where students decide to apply and enroll. With that in mind, some colleges work hard to make their tours distinctive.

But a good tour without strong follow-up efforts can be a missed opportunity. That’s what the admissions staff at California Polytechnic State University at San Luis Obispo believed.

There was just one wrinkle. To follow up with prospective students who had recently toured the campus, Cal Poly’s admissions staff would have to know who they were. And it didn’t always have that information.

The university does ask campus visitors to register for a tour, but does not require them to, says Al Nunez Jr., associate director of multimedia communications. That meant figuring out whom to reach out to required some guesswork.

Cal Poly first looked into a bar-code system, and learned it would cost tens of thousands of dollars, Mr. Nunez says.

Then, Mr. Nunez used a QR code to board a flight, and a light bulb went on. “If airlines can do it,” he wondered, “how do we do it?”

Mr. Nunez asked Amy Anderson, a student who worked in the admissions office, to look into it. Ms. Anderson, a sociology major who has since graduated, found a free program to generate the codes and tried it out with the university’s system.

Cal Poly started sending registered visitors QR codes, which they could print out or pull up on a smartphone. Tour guides armed with iPods or iPads could quickly scan them in, leaving the admissions staff with a clear idea of whom to reach out to after a tour. (Visitors who do not register in advance are asked to fill out a short form on the campus.)

While a number of other colleges have expressed interest in Cal Poly’s system, the admissions staff is not aware of any other campus that uses QR codes to check people in for tours, Mr. Nunez says.

Neither is Jeff Kallay, who spends a lot of time helping colleges improve their tours in his work as vice president for consulting at TargetX, a firm specializing in student recruitment.

But as obvious as the idea of tracking visitors to follow up with them might sound, many colleges don’t do it, say Mr. Kallay and his TargetX colleague Emily K. Welsh. A surprising number don’t have any sort of registration process, says Ms. Welsh, director of client experience. “How do you know who the heck is on your campus if you’re not asking them to register?”

QR codes aren’t widely used, and might not be the best fit for every campus tour, Mr. Kallay says, though they may well be a good fit for Cal Poly’s more tech-savvy pool.

But however they do it, campus tours should find a way to track who actually shows up for visits, Mr. Kallay and Ms. Welsh say. And they should make sure it doesn’t require students to bother with putting all of their personal information on one more registration card.