Bill Gates is something of a model for education skeptics. Mr. Gates — like Steve Jobs, Mark Zuckerberg and Oprah Winfrey — dropped out of college. If they didn’t need a college degree, the skeptics suggest, maybe you don’t need one, either.

Mr. Gates has just published a blog post with something of a reply: Yes, you do need one.

“Although I dropped out of college and got lucky pursuing a career in software, getting a degree is a much surer path to success,” he writes.

“College graduates are more likely to find a rewarding job, earn higher income, and even, evidence shows, live healthier lives than if they didn’t have degrees. They also bring training and skills into America’s work force, helping our economy grow and stay competitive.”

He adds, “It’s just too bad that we’re not producing more of them.”

The post is tied to an interview Mr. Gates has done with Cheryl Hyman, the chancellor of the City Colleges of Chicago, the city’s network of community colleges. During her five-year tenure, the system has started to raise its abysmally low graduation rate. One of her main pushes has been simplifying the course-selection process, so students know what courses they need to take and can enroll in them. The complexity of that process at many colleges is a bigger problem than many people realize.