While folk music has long addressed social and political concerns, it wasn't until the 1960s protest movement that rock, still in its infancy, began to take notice. Bob Dylan's infamous shift from acoustic to electric more or less signals the start of Political Rock. Other acts soon followed his example -- among them the Byrds, Neil Young, and Crosby, Stills and Nash -- cribbing notes from folksingers like Phil Ochs and Joan Baez as well. Political Rockers sing of social and political discontent, and generally fall left-of-center, although they haven't had much of a unifying theme since the sweeping struggles of the '60s and the early '70s. In the consumer-crazed late '70s and early '80s, Punk picked up the political banner and transformed it into something altogether angrier and more challenging. Many mainstream artists of that period meanwhile took occasional stands and supported their favorite causes celebre. U2 for instance, built much of their early popularity on their political flag-waving, while a veritable who's who of notable pop stars assembled for every "We are the World" opportunity to demonstrate their social consciences to fans. Whether they did so out of an urge to change society or out of marketing savvy is for the listener to decide. The more recent Political Rock catalog includes everything from the melodic Punk of the Clash, to the Australian activist rock of Midnight Oil, to the industrialized soapbox rants of Rage Against the Machine.