I had been out of school for 12 years when I started the OMSCS program (and my last degree wasn't in CS), but have also been working in the field for a while.

I had been out of school for 12 years when I started the OMSCS program (and my last degree wasn't in CS), but have also been working in the field for a while. I'd strongly suggest brushing up on: * Linear algebra, matrix arithmetic, some calculus (you run into differentials occasionally, esp in ML coursework). * Be comfortable with basic algorithm analysis, namely "Big O" assessment. (There's a course for more in-depth analysis of algorithms should you choose that path...) * Bone up on Python, Java and C if you're not already proficient. Some classes occasionally use R as well (mostly data science). * Be comfortable with Git. It's used by almost every class for group work and distribution for codebases. I always see a lot of folks battle with this every semester.