Electronic decision-support systems appear to enhance care, but improving both tools and work practices may optimize outcomes. Using qualitative methods, the authors' aim was to evaluate perspectives about using the Patient Panel-Support Tool (PST) to better understand health care workers' attitudes toward, and adoption and use of, a decision-support tool. In-depth interviews were conducted to elicit participant perspectives about the PST-an electronic tool implemented in 2006 at Kaiser Permanente Northwest. The PST identifies "care gaps" and recommendations in screening, medication use, risk-factor control, and immunizations for primary care panel patients. Primary care physician (PCP) teams were already grouped (based on performance pre- and post-PST introduction) into lower, improving, and higher percent-of-care-needs met. Participants were PCPs (n=21), medical assistants (n=11), and quality and other health care managers (n=20); total n=52. Results revealed that the most commonly cited benefit of the PST was increased in-depth knowledge of patient panels, and empowerment of staff to do quality improvement. Barriers to PST use included insufficient time, competing demands, suboptimal staffing, tool navigation, documentation, and data issues. Facilitators were strong team staff roles, leadership/training for tool implementation, and dedicated time for tool use. Higher performing PCPs and their assistants more often described a detailed team approach to using the PST. In conclusion, PCP teams and managers provided important perspectives that could help optimize use of panel-support tools to improve future outcomes. Improvements are needed in tool function and navigation; training; staff accountability and role clarification; and panel management time.