W. P. van Stockum Jr. entered the family publishing and bookselling business at 15 years old. After leaving the company he dedicated his time to a number of activities including the preparation of a book on 4 centuries of publishing in the Netherlands (La librairie, l’imprimerie et la presse en Hollande à travers quatre siècles) for the International Publishers Congress in Amsterdam in 1910, which he presided over.