 This is a Phase 3, placebo-controlled, double-blind randomized study with an open-label phase designed to evaluate the efficacy and safety of adalimumab 40 mg administered every other week in adult patients with active axial spondyloarthritis SpA who are not diagnosed with ankylosing spondylitis, psoriasis, or psoriatic arthritis and who have had an inadequate response or intolerance to one or more nonsteroidal anti-inflammatory drugs NSAIDs or had a contraindication to NSAIDs. Participants receive adalimumab or placebo for 12 weeks during the double-blind phase of the study. Following the double-blind phase, all remaining participants enter the open-label phase of the study in which they receive open-label adalimumab for up to 144 weeks. Efficacy endpoints include the Assessment of Spondyloarthritis International Society ASAS response criteria for patients with SpA. These response criteria were used to determine participants who were responders. ASAS response involves evaluations in the following 4 domains: participants global assessment of disease activity, pain, function, and inflammation. The patients global assessment of disease activity score is assessed using a 100 millimeter mm visual analog scale VAS; 0 for no disease activity to 100 for severe disease activity. Pain is represented as a total back pain score and is assessed using a 100 mm VAS 0 for no pain to 100 for most severe pain. Function score is represented as the Bath Ankylosing Spondylitis AS Functional Index BASFI 100 mm VAS score average of the ability to perform 10 activities, each scored as 0 for easy to 100 for impossible. Inflammation is determined using the morning stiffness overall level score 0 for none to 10 for very severe and duration score 0 for 0 hours to 10 for 2 hours of the Bath AS Disease Activity Index BASDAI mean of these items 5 and 6 scores. In addition, the BASDAI is used as an efficacy endpoint. The BASDAI is used by the participant to assess hisher disease activity. Using VAS scales, the participant answers 6 questions pertaining to symptoms experienced over the past week. For 5 questions levels of: fatiguetiredness; AS neck, back, or hip pain; painswelling; discomfort at areas tender to touch or pressure; and morning stiffness, the response scale is 0 none to 10 very severe. For 1 question duration of morning stiffness, the response scale is 0 0 hours to 10 2 or more hours. 