Father Harry Thiel's interest in working for the Hmong Hill Tribe people stems from a visit to Laos in 1962 when he first came in contact with them. Appointed pastor of Thabom village in Luey in 1964, he was able to begin visiting the Hmong who lived in Luey province. In 1964 he went to Laos again to study the Hmong language. Back in Thailand he began visiting Hmong villages and eventually set up a center in the village of Khek Noi, in Luey. Communist insurgency made it impossible for Father Harry and his catechumens to remain in Khek Noi in 1968, so they moved to church property in Luey.

In 1969, Father Harry was appointed to the pastorate of Holy Redeemer Church, so he had curtail his ministry to the Hmong for five years. Finally in 1979 he was once more able to devote himself full time to the Hmong apostolate. In that year he took up residence in Chiengmai where he set up a center to educate Hmong children and train catechists. Ever since, Father Harry has expanded his center and now tramps around the mountains ministering to the spiritual needs of Hmong Catholics in 46 villages in the North, with the help of 12 Catechists. Many other villages have been turned over to the pastoral care of other missionaries. At present Father Harry's charges number 1,500 Catholics and 2,500 catechumens. Father Harry is preaching the word of God in the best tradition of the Redemptorists: to the poor and most abandoned.

On May 22,1998, our Vice Province appointed two confreres, Father Paul Phakphum Sakulvivat and Brother Prachob Huearngkaew to begin a mission in the Province of Nan. The new Missionnaries soon found three Catholic families in the city of Nan, so their apostolate began. Travel in Nan is very difficult, with mountain roads throughout the Province. The Missionaries of Nan also care for the two villages of Sop Kok and Huey Leab where Father Harry Thiel CSSR had evangelized during his travels among the Hmong people. Father Phakphum pioneered this apostolate for more than a year. In September, 1997, two young priests, Father Virach Amornpattana and Fr. Phattarapong Srivorakul joined Brother Prachob in spreading the faith. On October 31, 1997 , His Excellency, Bishop Sangvan, Bishop of Chiangmai, invited our Congregation to send Missionaries to care for the Karen people in Amphur Mae Chem with several Catholic villages in the surrounding mountains. The Redemptorist Apostolate has spread to new areas of Thailand!