Objectives: Healthcare organization leaders' support is critical for successful implementation of new practices, including complementary and integrative health (CIH) therapies. Yet little is known about how to garner this support and what motivates leaders to support these therapies. We examined reasons leaders provided or withheld support for CIH therapy implementation, using a multilevel lens to understand motivations influenced by individual, interpersonal, organizational, and system determinants. Design and setting: We conducted qualitative interviews with leaders in seven Veterans Health Administration medical centers that offered at least three CIH therapies to Veterans and were identified as early adopters of CIH therapies. Subjects: Participants included 12 executive leaders and 34 leaders of key clinical services, including primary care, mental health, physical medicine and rehabilitation, and pain. Measures: We used a thematic analysis to examine leaders' narratives of barriers and facilitators to implementation including their attitudes toward CIH therapies, perceptions of evidence, engagement in implementation, and decisions to provide concrete support for CIH therapies. Drawing from Greenhalgh's Diffusion of Innovation framework, we organized themes according to the influence of individual determinants, two levels of inner setting, and outer system context on CIH implementation. Results: Leaders' decisions to provide or withhold support were driven by considerations across multiple levels including (1) individual attitudes/knowledge, perceptions of evidence, and personal experiences; (2) interpersonal interactions with trusted brokers, patients, and loved ones/colleagues/staff; (3) organizational concerns surrounding relative priorities, local resources, and metrics/quality/safety; and (4) system-level policy, bureaucracy, and interorganizational networks. These considerations interacted across levels, with components at organizational and system levels sometimes prevailing over individual perceptions and experiences. Conclusions: Garnering leaders' support for CIH therapy implementation should address their considerations at multiple levels. Implementation strategies designed to shift individual attitudes alone may be insufficient for securing leaders' support without attention to broader organizational and system-level contextual issues.