Kelly has many irons in the fire. He studied Mathematics and Physics at MIT, then went on to graduate work in Superstring Theory/M-Theory, working with "Genius Grantees" (MacArthur Fellows) such as Daniel Friedan, Nathan Seiberg, and Stephen Shenker. He then went on to code, joining a startup that eventually wen public in the late 90's. After that he decided to move to Berlin and come on board a startup working on natural language understanding.

When the bubble burst, he jumped back into an academic setting and joined the Max Planck Institute for Gravitational Physics where he worked on software systems used to help simulate black hole mergers. Jumping the fence again he went back to industry and worked a Mental Images/NVIDIA writing 3D rendering software. After that he worked on natural language understanding at a startup, 42, creating a system, based off of IBM'S Watson, that is able to answer general knowledge questions. After a brief stint as the Director of Machine Learning at another Berlin startup, he joined Mozilla where he now leads the machine learning group working on STT, TTS, and NLU.