 If you are found to be eligible, you will receive lenalidomide plus rituximab. This study will be done in 2 phases. In the Phase I portion of this study, 6 dose levels of lenalidomide will be studied. The same level of rituximab will be given to all participants. Between 3-6 participants will be treated at each dose level. Those enrolled first on this study will receive the lowest dose of lenalidomide plus rituximab. After treatment, each dose level of lenalidomide will be evaluated to check for any intolerable side effects. The dose of lenalidomide that you will receive will depend on the time that you enter this study and the side effects of those participants that entered the study before you. Once a dose has been assigned to you, it will not increase, but it could decrease or remain the same for a while if you have intolerable side effects. Once the highest tolerable dose of lenalidomide has been found, additional participants will receive that dose during the Phase II portion of this study. 