Pennathur Subramaniam Iyer, donated his estate in Minjur to set up a school. Hence the school / trust is named after him in 1899. The revenue from the estate was to be used to run a Sanskrit School in Mylapore. But the project was not taken up for many years. In 1905, the trust set up P.S. High School to cater to about 300 students. Over the years, P.S. Charities opened more schools in and around Mylapore.