Background <p>Valid and reliable measures for assessing the sustainability of complex, multicomponent, and interdisciplinary healthcare interventions are lacking. The study objective was to develop a multidimensional instrument for use to assess the sustainability of complex, interdisciplinary, healthcare interventions implemented in acute care settings.</p> Methods <p>Content experts participated in a modified Delphi study of electronic REDCap^® measures. Round 1, composed of 49 structured and unstructured questions, was analyzed using descriptive statistics and content analysis. In rounds 2 and 3, experts rated items derived from round 1 to provide evidence of sustainability on a 5-point Likert-type scale. Questions rated by &gt; 75% of the experts as important were retained for the final measure.</p> Results <p>Ten experts representing areas of quality improvement, sustainability, and implementation science participated in rounds 1 and 8 experts in rounds 2 and 3, respectively. Round 1 statements with a median value of &lt; = 6 on the 10-point Likert scale or &lt; = 3 on the 4- or 5-point Likert scale were retained. The items retained, modified, and added in Round 2 included 53 items. Questions rated by &gt; 75% of the experts as important were retained for the final measurement; conversely, questions rated by ≤ 25% of the experts as important were discarded. Twenty-five items with associated %s expert ratings of “important” (between 25% and 75% from Round 2) were included in Round 3. The modified Delphi process resulted in a final 37-item scale.</p> Conclusions <p>Using a modified Delphi technique, experts reported varying perceptions of sustainability. However, commonalities in key areas were successfully translated into the Sustainability Measure for Healthcare for assessing the sustainability of complex, multicomponent interventions.</p>