Inclusion Criteria:

• Understand and voluntarily sign an informed consent form.
• Age >/= 18 at the time of signing the informed consent form.
• Able to adhere to the study visit schedule and other protocol requirements.
• Untreated indolent non-Hodgkin's lymphoma stage III-IV including small lymphocytic lymphoma, marginal zone lymphoma, grade 1 or 2 follicular lymphoma.
• At least one measurable lesion according to the Response Evaluation Criteria in Solid Tumors (RECIST) Committee criteria of greater than 1.5cm.
• ECOG performance status of </= 2 at study entry.
• Laboratory test results within these ranges: Absolute neutrophil count >/= 1.5 x 10^9/L; Platelet count >/=100 x 10^9/L; Serum creatinine </= 2.0 mg/dL; Total bilirubin </=1.5 mg/dL; AST (SGOT) and ALT (SGPT) </=2 x ULN or </=5 x ULN if hepatic metastases are present.
• Disease free of prior malignancies for >/= 5 years with exception of currently treated basal cell, squamous cell carcinoma of the skin, or carcinoma "insitu" of the cervix or breast.
• All study participants must be registered into the mandatory RevAssist® program, and be willing and able to comply with the requirements of RevAssist®.
• Females of childbearing potential (FCBP) must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10 -14 days prior to and again within 24 hours of prescribing lenalidomide and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control, one highly effective method and one additional effective method AT THE SAME TIME, at least 4 weeks before she starts taking lenalidomide. FCBP must also agree to ongoing pregnancy testing.
• Men must agree to use a latex condom during sexual contact with a female of child bearing potential even if they have had a successful vasectomy.
• For patients with bulky disease (tumors >5cm) must be able to take aspirin (81 mg or 325 mg) daily as prophylactic anticoagulation (patients intolerant to ASA may use warfarin or low molecular weight heparin.

Exclusion Criteria:

• Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from signing the informed consent form.
• Pregnant or breast feeding females.
• Any condition, including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study or confounds the ability to interpret data from the study.
• Use of any chemotherapy or experimental therapy within 28 days of enrollment.
• Known hypersensitivity to thalidomide.
• The development of erythema nodosum if characterized by a desquamating rash while taking thalidomide or similar drugs.
• Any prior use of lenalidomide.
• Concurrent use of other anti-cancer agents or experimental treatments.
• Known positive for HIV or infectious hepatitis type B or C.