OBJECTIVES: Evaluate the reliability and validity of the LIT, a 10-item PRO assessment of the impact of SLE on the patient’s life.  Additionally, the acceptability and feasibility of LIT from the patient’s and physician’s perspectives was assessed. METHODS: Baseline data were collected on 325 SLE patients during a clinic visit. Patients completed the LIT, SF-36v2, LupusQoL, and PHQ-9. Both patients and physicians completed a questionnaire on the feasibility/acceptability of LIT. Patients completed the LIT 7-14 days following baseline to assess test-retest reliability. Physicians completed disease activity assessments (SELENA-SLEDAI, BILAG, and SLICC/ACR Damage Index), a physician’s global assessment (PGA) and patient’s recent flare status. Reliability was evaluated using internal consistency methods (Cronbach’s alpha) and test-retest methods (intra-class correlation). Convergent validity was evaluated by correlating LIT scores with scale scores from the SF-36v2, LupusQoL, and PHQ-9. Construct validity was evaluated by comparing mean LIT scores across patients that differed in PGA ratings and presence/absence of a recent flare.  ANOVA and Student’s t-tests were used to test mean differences in LIT scores across patient groups. It was hypothesized that LIT scores would be lower among patients with lower PGA ratings and no recent flare. RESULTS: Internal consistency and test–retest reliabilities of LIT were 0.90 and 0.88, respectively. Convergent validity correlations ranged from -0.63 to -0.75 with SF-36v2 scales, from -0.42 to -0.75 with LupusQoL scales, and 0.75 with the PHQ-9.  Mean LIT scores differed as hypothesized across patients with different PGA ratings (F=5.8, df=2, p=0.004).  Mean LIT scores differed between patients with and without a recent SLE Flare (t=2.11, p=0.038).  The majority (>70%) of both patients and physicians found LIT to be acceptable and feasible to administer in a clinic setting. CONCLUSIONS: The LIT is a reliable and valid instrument for assessing the impact of SLE on patient’s functioning and well-being.