Churches were established to spread religion and treat diseases according to the methods of modern medicine.

Later, the letters of Khru Si Hom Wichai, the first Chiang Mai resident to go to the United States, written from San Francisco, were used as textbooks.

They taught the Bible, reading and writing local scriptures, mathematics, and basic English.

He asked for donations to buy 22 acres of land from Borneo Company, which is the current location of Prince Royal's College.

Dr. Harris devoted 46 years of his life to the school before retiring and returning to the United States in 1940.

The ultimate aim of the activities is the development of character and making the students be skilled workers.

On February 2, 2009, Carl XVI Gustaf of Sweden visited his honored scout in this school.

The Prince Royal’s College focuses on English, mathematics, Chinese, science and computer programs.

The Prince Royal’s College is supported by the Stock Exchange of Thailand (SET) by building activities about sufficiency economy such as “Bottle Bank”, “1 person 1 job” and “Saving money”.

The Harris Mini Marathon is a charity run held by the school every year on the second Saturday of November.

As well as contributing to the school's funds, but in 2016, it was not held due to the passing of His Majesty King Bhumibol Adulyadej.

Every year, Christian Communications Institute (CCI) from Payap University has performances about the story of God and faith for moral and ethical development.

The Harris House Museum is the school's first main buildings built of teak wood.

The Harris Institute, or "100-Year Building" was built to be a center for the development of multi-intelligence learning, promoting students' skills and abilities in thinking.

The design focuses on giving children as much space for activities and expression as possible, with a total of 4 floors and an area of 4,000 square meters.

On 27 July 2011, Her Royal Highness Maha Chakri Sirindhorn attended the official opening ceremony of the Harris Institute.

When the school was collected enough funds, Mr. Van Allen Harris, the younger brother of Rev.

Dr. Harris, who was an architect and engineer, traveled to Chiang Mai, designed, and supervised the construction of the church until it was completed in 1930.

The theater was built along with the school chapel in 1929 for multipurpose use as a venue for student learning activities, meetings, performances and even ethics training.

The cornerstone monument was built by the Prince Royal's College Alumni Association to commemorate the founding of the school.

The plaque from the renaming of the school, bestowed by His Royal Highness, Crown Prince Maha Vajiravudh on January 2, 1906, was enshrined there.