Guideline implementation requires clinician knowledge but may be influenced by pre-existing beliefs and biases. We assessed the association of these clinician factors with lipid management following the release of the 2013 American College of Cardiology/American Heart Association cholesterol guidelines. In the PALM registry, 774 clinicians completed a survey to assess their knowledge of the 2013 American College of Cardiology/American Heart Association guidelines, belief in statin benefit, and statin safety concerns. The association of these factors with statin use, statin dosing, and low-density lipoprotein cholesterol (LDL-C) levels were assessed in the 6,839 patients treated by these clinicians between May and November 2015. Overall, 63.9% of clinicians responded to at least 3 out of 4 hypothetical scenarios in concordance with guideline recommendations (good tested knowledge), 88.4% reported belief in statin benefit, and 15.4% raised concerns about statin safety. Belief in statin benefit was more prevalent among cardiologists, who represented 48.8% of the clinicians surveyed, and concerns regarding statin safety were higher among noncardiologists and clinicians in an academic setting. Guideline knowledge was not associated with a difference in statin use (74.1% vs 73.8%, p = 0.84) and achievement of LDL-C level <100 mg/dl (54.7% vs 52.4%, p = 0.07). However, patients treated by clinicians who reported belief in statin benefit were more likely to receive guideline-recommended statin intensity (41.9% vs 36.9%, p = 0.03), whereas patients treated by clinicians expressing statin safety concerns were less likely receive statins of at least guideline-recommended intensity (36.8% vs 42.5%, p = 0.001) and to achieve an LDL-C <100 mg/dl (44.1% vs 56.1%, p <0.001); the latter persisted after multivariable adjustment (odds ratio 0.75, 95% confidence interval 0.63 to 0.89). In conclusion, clinician beliefs regarding benefits and risks of statins were significantly associated with guideline adherence and patients’ achieved LDL-C levels, whereas clinician knowledge of guideline recommendations was not.