In contemporary political discourse, the words “liberal” and “liberalism” are sometimes contentious, even provocative. Here we try to trace the complex history of this particular ideology. What are its origins? What are its key features? And how has it changed? For more than three centuries, the hallmark of liberalism has been the attempt to promote individual liberty. But this very broad goal leaves room for liberals to disagree among themselves as to what exactly liberty is and how best to promote it. Indeed, this disagreement is now so sharp that liberalism is split into two rival camps of “neoclassical” and “welfare” liberals. Later in this chapter we shall see how this split occurred. But fi rst we need to look at that broad area of common ground on which all liberals meet-the desire to promote individual liberty.