This study determines the impact of provider knowledge and attitude on implementation of guidelines: spirometry, peak flows, patient assessments, action plans, severity assessment, and anti-inflammatories. A self-administered survey conducted in academic family practice sites in Buffalo, NY assessed knowledge, self-reported use, and perceived usefulness. Knowledge was associated with regular use of peak flows (p = 0.048) and anti-inflammatories (p = 0.01). Positive attitude was associated with regular use of spirometry (p = 0.03), peak flows (p < or = 0.001), patient assessments (p = 0.02), action plans (p = 0.046), anti-inflammatories (p < or = 0.001), and severity assessment (p < or = 0.001). Perceived usefulness is critical to implementing asthma guidelines. Interventions to improve provider adherence must address attitude.