A small church comprising an 11thc. nave with a plain N doorway, a 19thc. N porch and 14thc. S chapel which was rebuilt in the 19thc. A W tower was demolished before 1791; the W wall, with its bell-cote, was rebuilt in the 19thc. The square chancel dates from the 11thc. Some herringbone masonry is visible in nave and chancel.

Selham is mentioned in the Domesday Survey, but no church. In the late 12thc. or early 13thc. (before 1204) William de Braose gave the church to Rusper Nunnery (VCH vol. 2, 63ff). Rusper Nunnery also held the churches of Ifield, Warnham and, from 1231, Horsham.

The chancel arch has been variously dated before and after 1066. Nairn and Pevsner ask: 'Could not Saxon pieces have been used by a mason of 1130-40 who then himself provided for the missing parts his Norman formulae and carved the capitals in his style, in itself inspired by Viking tradition?' On stylistic grounds, however, both capitals and all four impost blocks appear to have been carved by the same workshop, probably for the same ensemble and at the same time. The foliage and fat double strands, in particular, are consistent throughout. There must be some doubt, however, that the pieces were carved for a chancel arch of precisely this design. While the lower impost blocks sit happily on top of the capitals, their E sides appear to have been trimmed. The upper impost blocks seem to have been more drastically cut down to fit their present position, and are wider than those below. The double impost block is perhaps one of the reasons this ensemble has been dated to the Anglo-Saxon period in the past (e.g. Taylor and Taylor), but it was more probably carved in the last quarter of the 11thc. The large volutes find a parallel in the W tower of Sompting (q.v.).The font may date from the same period.