Coolham is a small village in the civil parish of Shipley and the Horsham District of West Sussex, England. It is located at the crossroads of the A272 and B2139 roads 2.8 miles southeast of Billingshurst.
At the crossroads is an old timber-framed inn, the Selsey Arms, formerly the Duke's Head, and before that The King of Prussia.
During the Second World War there was an Advanced Landing Ground nearby called RAF Coolham, used to support the D-Day landings. This was only in use for about eighteen months, and had almost no permanent buildings. The airmen lived under canvas. Both Polish and British airmen were stationed there, and there is a monument outside the Selsey Arms which lists the names of those who died. The land has long since been reclaimed for agricultural purposes, but there is still a footpath around the field, with trees planted at intervals to commemorate the dead airmen. Each tree has a name plaque attached.
There was once a prominent Quaker community in Coolham, and the "Blue Idol" meeting house, a timber-framed building, still exists.