The Association of Christian Schools International (ACSI) is an association of evangelical Christian schools. ACSI has members in the United States and around the world.
ACSI was originally formed in 1978 out of the merger of three smaller groups, after which several other similar groups joined. Originally based in California, it is now headquartered in Colorado Springs, Colorado.
ACSI provides accreditation for primary and secondary schools (but not colleges or universities) that are faith-based, along with legal and other services as well as curriculum under the trade name Purposeful Design Publications. Although it offers many services for profit, ACSI is legally organized as a 501(c)(3) non-profit entity to which deductible charitable donations can be made.