In this presentation we explore two efforts designed to promote interoperability between the OPeNDAP data access protocol and the OGC WFS and WCS protocols. The first is based on MapServer, an open-source development environment for building spatially-enabled Internet applications. Among other things, MapServer may be used as an OGC WFS and WCS server. As part of the effort described in this presentation the Simple Features Library (OGR) and the Geospatial Data Abstraction Library (GDAL) have been extended to support access to OPeNDAP enabled data sources. Because the OGR and GDAL libraries are core components of MapServer this extension enables OGC WFS and WCS access to OPeNDAP data sets. The second interoperability effort addressed is based on the THREDDS Data Server (TDS). The TDS is a new technology from Unidata, combining previous implementations of THREDDS Catalog Services with integrated data serving capabilities, including OPeNDAP and WCS. Because the TDS can operate as an OGC WCS server and as an OPeNDAP client it may be used as an OPeNDAP-WCS gateway. In both cases, metadata incompatibilities must be addressed. In the case of MapServer this is done via the OPeNDAP Ancillary Information Services capability, while in the TDS case it is done via routines that automatically convert metadata from some of the standards commonly used by OPeNDAP data providers, such as COARDS, to the metadata needs of WCS.