Bok married fellow astronomer Priscilla Fairfield in 1929, and for the remainder of their lives, the two collaborated so closely on their astronomical work that the Royal Astronomical Society said "from that point on it is difficult and pointless to separate his achievements from hers". The Boks displayed such great mutual enthusiasm for explaining astronomy to the public that "The Boston Globe" described them in 1936 as "salesmen of the Milky Way". They worked together on research and co-authored academic papers, and their general interest book "The Milky Way" went through five editions and was "widely acclaimed as one of the most successful astronomical books ever published".