Knowledge acquisition is a goal of residency and is measurable by in-training exams. Little is known about factors associated with medical knowledge acquisition. To examine associations of learning habits on medical knowledge acquisition. Cohort study of all 195 residents who took the Internal Medicine In-Training Examination (IM-ITE) 421 times over 4 years while enrolled in the Internal Medicine Residency, Mayo Clinic, Rochester, MN. Score (percent questions correct) on the IM-ITE adjusted for variables known or hypothesized to be associated with score using a random effects model. When adjusting for demographic, training, and prior achievement variables, yearly advancement within residency was associated with an IM-ITE score increase of 5.1% per year (95%CI 4.1%, 6.2%; p < .001). In the year before examination, comparable increases in IM-ITE score were associated with attendance at two curricular conferences per week, score increase of 3.9% (95%CI 2.1%, 5.7%; p < .001), or self-directed reading of an electronic knowledge resource 20 minutes each day, score increase of 4.5% (95%CI 1.2%, 7.8%; p = .008). Other factors significantly associated with IM-ITE performance included: age at start of residency, score decrease per year of increasing age, -0.2% (95%CI -0.36%, -0.042%; p = .01), and graduation from a US medical school, score decrease compared to international medical school graduation, -3.4% (95%CI -6.5%, -0.36%; p = .03). Conference attendance and self-directed reading of an electronic knowledge resource had statistically and educationally significant independent associations with knowledge acquisition that were comparable to the benefit of a year in residency training.