Eric von Schmidt and Jim Rooney, who co-authored Baby, Let Me Follow You Down, played big roles in many of the events they chronicle in this “illustrated history of the Cambridge folk years.” Where the book is concerned, that personal involvement constitutes their biggest asset and largest problem. On the one hand, von Schmidt and Rooney genuinely care about and understand the music scene in Cambridge, Massachusetts, which spawned an amazing number of major talents in the late 1950s and early 1960s. Neither has enough perspective to differentiate what would interest us all from what only the participants might want to read, however. The result is a weakly organized, unindexed, occasionally ungrammatical tale that wanders too often into abstruse nostalgia but that will nevertheless reward patient readers with much fascinating information.