Objective: To investigate the effectiveness of conservative nonpharmacologic therapies on pain, disability, physical capacity, and physical activity outcomes in patients with degenerative lumbar spinal stenosis (LSS). Data Sources: Systematic search of MEDLINE, EMBASE, CENTRAL, and PsycINFO from inception to November 4, 2019, without language restrictions. Study Selection: Pairs of review authors independently identified randomized controlled trials published in peer-reviewed scientific journals reporting on the effects of rehabilitation interventions on pain intensity (back or leg), disability, symptom severity, physical capacity, physical activity behavior, or adverse events (secondary outcome) in adults with LSS. The search identified 1718 records; data from 21 reports of 19 trials (1432 patients) were included. Data Extraction: Review author pairs independently extracted data and assessed included studies. We assessed risk of bias with the Cochrane tool, and overall study quality with the Grading of Recommendations Assessment, Development and Evaluation classification. Data Synthesis: We pooled data using random-effects meta-analyses; treatment effects were reported as mean differences (MD) and 95% confidence intervals (CI). Directed exercise and manual therapy was superior to self-directed or group exercise for improving short-term walking capacity (MD, 293.3 m; 95% CI, 61.7-524.9 m; low-quality evidence), back pain (MD, –1.1; 95% CI, –1.8 to –0.4; moderate quality evidence), leg pain (MD, –.9; 95% CI, –0.2 to –1.5; moderate-quality evidence), and symptom severity (MD, –0.3; 95% CI, –0.4 to –0.2; low quality evidence). There is very low quality evidence that rehabilitation is no better than surgery at improving intermediate- or long-term disability. Single trials provided conflicting evidence of effectiveness for a variety of therapies. Conclusions: For patients with LSS, there is low- to moderate-quality evidence that manual therapy with supervised exercises improves short-term walking capacity and results in small improvements in pain and symptom severity compared with self-directed or group exercise. The choice between rehabilitation and surgery for LSS is very uncertain owing to the very low quality of available evidence.