| Assistant Professor | Philosophy and Religion, Olivet College, Olivet, MI | 1960–1963 |
| Assistant Professor | Theology, Wheaton College, Wheaton, IL | 1963–1966 |
| Assistant Professor | Church History, Westminster Theological Seminary | 1966–1970 |
| Associate Professor | Church History, Westminster Theological Seminary | 1970–1978 |
| Professor | Church History, Westminster Theological Seminary | 1978–2004 |
| Associate Pastor | New Life OPC, Jenkintown, PA | 1979–1988 |
| Recd. by | Philadelphia Presby., PCA | 1988–2004 |
| Associate Pastor | New Life PCA, Ft. Washington, PA | 1988–2004 |
| Grace PCA, Vancouver, BC, Canada | 2006–2009 |
| Professor | of Church History & Chap., Redeemer Seminary, Dallas, TX | 2009 |
| Chaplain and prof. | Redeemer Theological Seminary, Dallas, TX | 2009–2013 |