He received his Bachelors of Arts Degree from Willamette University in Salem, Oregon majoring in US History and Religious Studies. Pastor Tim moved to Boston, MA and entered Boston University School of Theology majoring in Biblical Studies and Local Church Ministry receiving his Master of Divinity degree in 1983. While in Boston he work for the private non-profit Boston Aging Concerns.

Pastor Tim met his wife, Rev. Amy Overton-Harris (pastor of Trinity UMC in SE Portland) while studying At Boston University School of Theology. They married in 1984 and moved to Oregon in 1985 to begin serving in local congregations of the United Methodist Church. Tim and Amy have three children, Liz who is in her fourth  year at Wells College in New York, Petter who is a senior at Aloha High School, and Nick a freshman, also at Aloha High School. The Overton-Harris family makes their home in the Aloha area of Washington County.

Pastor Tim as served as the Associate Pastor at the Oregon City UMC. He served the Estacada and Marquam UMCs. He moved to Salem, Oregon and served as Associate Pastor of Morningside UMC. Tim and Amy served as co-pastors of the La Grande UMC in northeastern Oregon. They moved to the Aloha area in 1999 and were co-pastors of Christ UMC in Cedar Mill. Pastor Tim was appointed to Vermont Hills UMC in the summer of 2004.