# Multi-Threaded Issues

Starting with Microsoft® Windows® 95 and Microsoft Windows NT® 3.51, OLE provides support for multi-threaded applications, allowing applications to make OLE calls from multiple threads. This multi-threaded support is called the apartment model, it is important that all OLE components using multiple threads follow this model. The apartment model requires that interface pointers are marshaled (using CoMarshallInterface, and CoUnmarshalInterface) when passed between threads. For more information about apartment model threading, refer to the Win32 SDK documentation, and the OLEAPT sample (in Win32® SDK).