Purpose: This study aims to describe the development and psychometric evaluation of the Leadership Influence Self-Assessment (LISA©) tool. Background: LISA© was designed to help nurse leaders assess and enhance their influence capacity by measuring influence traits and practices and identifying areas of strength and weakness. Methods: Concepts identified in the Adams Influence Model and input from content experts guided the development of 145 items for testing. Administered to 165 nurse leaders, the assessment was subjected to exploratory factor analysis (EFA). Findings: EFA yielded a four-factor solution that comprised 80 items. Cronbach's alpha for factors ranged between 0.912 and 0.938. All factor loadings were >0.4; the smallest factor contained 14 items. Items grouped together in the theoretical model also clustered together in the EFA. Conclusions: Preliminary psychometric testing supports validity and reliability of the LISA© and its potential use as a tool to assess influence capacity for purposes of leadership development and research.