In 1931, Georges Gurvitch published Le temps présent et l’idée de droit social [Present Time and the Idea of Social Law], which, for the first time, at least to the author’s knowledge, introduced the concept of legal pluralism, which would later enjoy widespread use in legal theory and legal sociology. In support of such a pluralistic legal view of law, Gurvitch relied heavily on the writings of Hugo Sinzheimer, the German founder of the science of labor law. Sinzheimer’s core conception was that of “collective autonomy,” a central concept of labor law jurisprudence. This study compares the thought of Gurvitch and Sinzheimer, highlighting the relevance of their understanding of legal pluralism for the sociology of contemporary labor law.