AbstractBackgroundFrontline nurse managers influence the implementation of evidence‐based practices (EBP); however, there is a need for valid and reliable instruments to measure their leadership behaviors for EBP implementation in acute care settings.AimThe aim of this study was to evaluate the validity and reliability of the Implementation Leadership Scale (ILS) in acute care settings using two unique nurse samples.MethodsThis study is a secondary analysis of ILS data obtained through two distinct multisite cross‐sectional studies. Sample 1 included 200 registered nurses from one large Californian health system. Sample 2 was 284 registered nurses from seven Midwest and Northeast U.S. hospitals. Two separate studies by different research teams collected responses using written and electronic questionnaires. We analyzed each sample independently. Descriptive statistics described individual item, total, and subscale scores. We analyzed validity using confirmatory factor analysis and within‐unit agreement (awg). We evaluated factorial invariance using multigroup confirmatory factor analyses and evaluating change in chi‐square and comparative fit index values. We evaluated reliability using Cronbach's alpha.ResultsConfirmatory factor analyses in both samples provided strong support for first‐ and second‐order factor structure of the ILS. The factor structure did not differ between the two samples. Across both samples, internal consistency reliability was strong (Cronbach's alpha: 0.91–0.98), as was within‐unit agreement (awg: 0.70–0.80).Linking Evidence to ActionFrontline manager implementation leadership is a critical contextual factor influencing EBP implementation. This study provides strong evidence supporting the validity and reliability of the ILS to measure implementation leadership behaviors of nursing frontline managers in acute care. The ILS can help clinicians, researchers, and leaders in nursing contexts assess frontline manager implementation leadership, deliver interventions to target areas needing improvement, and improve implementation of EBP.