A massive open online course (MOOC) is a web-based class environment aimed at large-scale global participation and open access via the Internet. MOOCs are also a disruptive trend changing how education is delivered and funded throughout the world. In the spring of 2013, we developed and taught Vanderbilt’s first MOOC, entitled “Pattern-Oriented Software Architecture for Concurrent and Networked Software”(known as the “POSA” MOOC). This ten-week MOOC was an amalgamation of several courses on software design and programming taken by∼ 600 undergraduate and graduate students at Vanderbilt during the past decade. Enrollment in our POSA MOOC was more than 50 times (31,000+) that number, consisting of students with a wide range of background, interests, and expertise from scores of countries around the world. This paper describes observations and lessons learned from our experiences preparing and delivering the POSA MOOC. Where possible, we ground our observations in data from statistics collected via Coursera, which was the delivery platform we used for the POSA MOOC. We also discuss the broader implications of MOOCs on life-long learning and the role they play in improving the quality and productivity of software professionals in academia and industry.