The dissolution behavior of the ceramic waste form (CWF) is being investigated to support its qualification for disposal in the proposed repository at Yucca Mountain. The CWF consists of sodalite and glass phases and has been consolidated either by hot isostatic pressuring (HIP) or by pressureless consolidation (PC). In this paper we compare the dissolution behavior of the two materials using in MCC-1 type tests at 90°C in a simulated silicate groundwater. The test solutions were periodically exchanged limit feedback effects. The solid surface area to volume ratio was 10 m-1. Five types of samples were tested: (1) HIP CWF, (2) binder glass vitrified by HIP, (3) PC CWF, (4) binder glass vitrified by PC, and HIP sodalite. Boron releases were used to monitor glass dissolution; these were similar in tests with HIP CWF, HIP glass, and PC CWF, but about 3X higher in tests with PC glass. At the end of the tests, the surfaces of the reacted materials were examined with scanning electron microscopy for signs of preferential dissolution. Differences in the dissolution behaviors of the materials are described and the implications of the test results regarding the performance of the CWF in the disposal system are discussed.