Asthma is a health problem that afflicts many Canadians. Better methods are needed to provide primary care physicians with ways of implementing current guidelines into regular practice for optimal disease management. This study will test the benefits of providing computer-based decision-support for asthma to primary care physicians, with links to home monitoring for their patients. To add value and to ensure regular use for the physician for all of his/her patients, these computerized decision-support tools will be linked to an electronic prescribing and drug management system. The investigators will evaluate the effectiveness of the computer-based decision-support system by determining whether asthma patients of physicians who receive computer-assisted management tools have better disease control after 18 months of implementation compared to asthma patients of physicians who have the electronic prescription and drug management system alone. To answer this question, the investigators will conduct a cluster randomized controlled trial in a population of approximately 100 physicians in 40 clinics in Quebec, and a total of 2,880 of their patients with asthma.