St. Philomena School was first accredited in 1997 by the Northwest Association of Schools. In spring 2005, St. Philomena School received a full six-year term of Accreditation and established a SCHOOL IMPROVEMENT ACTION PLAN (SIP PLAN) to serve as a blueprint for the four key goals for the school. St. Philomena School went through the accreditation process during the 2022-2023 school year. St. Philomena School received a six-year renewal of accreditation.

Accreditation is just one way of ensuring the public that the school meets minimum environmental standards, has a valid school improvement plan, and is engaged in an on-going self-study and on-site peer evaluation process.