In 1919 van Sambeek was assigned to the Chilubula mission in the
Apostolic Vicariate of Bangweolo, in
Northern Rhodesia, now Zambia. For the next twelve years he worked with the government in developing Catholic schools. He threw himself into the work with great energy and enthusiasm. He opened the Teacher Training College of Rosa in 1927, and became the college's first principal. He was later made Education Secretary for the diocese. He wrote a number of school books including
Ifya Bukaya, which is still in use today. He had an extraordinary aptitude for languages, and wrote many books in the
Bemba language covering a range of subjects. Van Sambeek visited the
copperbelt for two weeks in 1929 with Fr. Louis Etienne. He recommended a separate mission to support the miners, but this was not accepted. In 1932 he took home leave, following which he was made
Prefect Apostolic of
Tukuyu in
Tanganyika. There he prepared a
Nyakyusa dictionary and a
Safwa grammar. He returned to Northern Rhodesia in December 1933 as Administrator of the new Mission Sui Juris of
Lwangwa. In 1934 he founded the Ilondola (Maria Magdalena de Puzzi) mission in
Chinsali District and the Chalabesa (St. Joseph) mission among the Bisa in the
Mpika District. In 1936 he established the missions of Katibunga, Christ the King (Mpika) and Mulilansolo near
Isoka and St. John the Apostle, (Chinsali). ==Vicar Apostolic and bishop==