The Romanesque church no longer survives. Of the 16thc church built on the site only the choir and vestry were constructed. A nave had been planned but it was never started. Transepts were finally added in 1863. Built into the W interior wall of the vestry is the head of a cross, formed by interlace. There is another, of nearly identical size and shape, also from Mid Calder, now in the National Museum of Scotland in Edinburgh.

In the first half of the 12thc, the Earl of Fife held the patronage. The parish became known as ‘Calder-Comitis’ (Calder of the Earl) to distinguish it from the parish of East Calder, called ‘Calder-Clere’. Sometime before 1161 (perhaps c.1159), the church had been gifted by Earl Duncan of Fife to the monks of Dunfermline. A record of a dedication occurs in 1241/1242. The church was rebuilt in the 2nd quarter of the 16thc, money being supplied by Peter Sandilands.

The cross heads from Mid Calder are of a type that seems specifically Romanesque (or at least no earlier than) with interlace that creates a cross pattern, the pointed ends of which are carved proud of the enclosing circle. There are closely related examples elsewhere, such as Kirkwall, Orkney (now in the Tankerness Museum) and Santiago de Compostela, Spain (now in the Popo Galego Museum). A church at Mid Calder existed certainly by 1158, but a more exact date for its construction cannot be ascertained. It seems not at all unlikely that the cross heads are of similar date. It is possible they were used as grave markers, but it is equally possible, and perhaps more likely since they are identical, that they were used as finials at the top of the E and W gable ends of the church.