When I've interviewed junior programmers (i.e., recent college graduates), I always ask them what projects they've worked on, especially class projects involving multi-person teams. After all, that's the kind of work they'll typically do in a real job.
If a person has never worked with other programmers on a project, that could require a steep learning curve.
The way to learn how to program is the way to learn just about anything: practice doing it. A lot.