Healthy Hearts Northwest (H2N) is a study of external support strategies to build quality improvement (QI) capacity in primary care with a focus on cardiovascular risk factors: appropriate aspirin use, blood pressure control, and tobacco screening/cessation. To guide practice facilitator support, experts in practice transformation identified seven domains of QI capacity and mapped items from a previously validated medical home assessment tool to them. A practice facilitator (PF) met with clinicians and staff in each practice to discuss each item on the Quality Improvement Capacity Assessment (QICA) resulting in a practice-level response to each item. We examined the association between the QICA total and sub-scale scores, practice characteristics, a measure of prior experience with managing practice change, and performance on clinical quality measures (CQMs) for the three cardiovascular risk factors. The QICA score was associated with prior experience managing change and moderately associated with two of the three CQMs: aspirin use (r = 0.16, p = 0.049) and blood pressure control (r = 0.18, p = 0.013). Rural practices and those with 2-5 clinicians had lower QICA scores.. The QICA is useful for assessing QI capacity within a practice and may serve as a guide for both facilitators and primary care practices in efforts to build this capacity and improve measures of clinical quality. This trial is registered with www.clinicaltrials.gov Identifier# NCT02839382, retrospectively registered on July 21, 2016.