Charles and Evelyn Tidwell spend approximately a fifth of their forty years overseas missionary work in Hong Kong, China. They went out to India in 1952 to serve in educational work: first as principal of a secondary school at Roorkee in North India, and then, following a furlough and of Charles getting a doctorate degree, several years at Spicer Memorial College.  Charles served as a teacher, librarian, and academic dean. In the General Conference session in 1966, he was asked to serve as Educational Director for the Southern Asia Division which he did for eight years.

 From 1974 to 1977 they worked at Mr. Klabat College in Eastern Indonesia.  Charles was Academic Dean there and Librarian, as well as teacher of several college classes.  There were challenging days at that college, for it was less than 10 years old when they went there and they were thrilled at the yearly growth that they could see and be a part of.

While headed for a furlough in the States in 1977, Charles was asked to stop by Hong Kong to visit the college and was requested to consider becoming president of South China Union College (later renamed Hong Kong Adventist College) with a specific challenge to get the college some sort of accreditation in connection with one of the U.S. Adventist colleges or universities.  They moved to Hong Kong in the late summer of 1977.

Possibilities were explored, and it was decided to seek an affiliation with the Western Association of Schools and Colleges, the accrediting body through which Loma Linda University was officially recognized. The next four years saw this dream become a reality.  There was a steady stream of visiting administrators and professional people from Loma Linda, and occasionally one of the administrators of SCUC visited Loma Linda and La Sierra.  Weeks and months were spent in committee meetings and report writing; a mountain of paper work!  A fulltime Loma Linda professor was assigned to the staff in Hong Kong.  The first program to be approved was that in Theology, followed very shortly by Biology.  Since Tidwell left Hong Kong much further progress has been made in widening the affiliation and scores of Loma Linda University (now La Sierra University) graduates have completed their degrees on the Hong Kong campus.

Charles was asked by the first national president of the South China Island Union Mission, Samuel Young to serve as secretary of that Union; this he did for four more years, serving the union in Hong Kong and in Taiwan, helping to maintain offices and communication between the two parts of the union.

In 1985, following the General Conference session in New Orleans, Charles was requested by the Far Eastern Division to transfer to Sri Lanka to serve as Union President there.These last five years of their service found the Tidwells in one of the most beautiful islands of the world, leading the work of the church in a very trying time, during unrelenting civil wars and political upheaval throughout the whole island.They retired in 1990 and established a residence in Washington State, but they have completed two volunteer assignments overseas.In 1991 Charles was the first worker to go back into isolated and backward Cambodia to re-establish an official SDA presence there and begin religious services again.In 1993 he went to Thailand to serve as interim president of the new Adventist college there and help it through one of its growing years until a regular appointee could be found and come to take over the work there.