For the first time, this book presents to Western readers a current in the late Soviet philosophy of the 1960s and 1970s known as the 'activity approach'. It had to some degree a counterpart in so-called cultural-historical psychology, but whilst the work of Vygotsky and Leontyev was received in the West decades ago, its sibling in philosophy has remained virtually unnoticed. Started by Evald Ilyenkov in the early '60s, the activity approach soon became an intellectual mode, leading to several different interpretations of human activity and challenging Marx and Lenin.