I studied finance in college. A few years later I asked a similar question, ended up enrolling as a post-bac student, and taught myself web development. First,

I studied finance in college. A few years later I asked a similar question, ended up enrolling as a post-bac student, and taught myself web development. First, you need to figure out exactly what you want to learn. By theoretical, what do you mean? If your goal is to be on the same level as other programmers who are CS grads, then you might consider digging into algorithms and data structures and discrete math. This is pretty much the base of anything theoretical you'll do in computer science. If you're in it to learn, go the udacity route. If, after completing all of their courses, you still feel you have some gaps, then you can go back to school if need be. If, on the other hand, your goal is to go into research, then you'll just have to bone up and go back to grad school to be taken seriously. In research, credentials matter.