Harmonization is the standardization of specifications for related measures with the same measure focus (for example, influenza immunization of patients in hospitals or nursing homes); related measures for the same target population (for example, eye exam and HbA1c for patients with diabetes); or definitions applicable to many measures (for example, age designation for children) so that they are uniform or compatible, unless differences are justified (in other words, dictated by the evidence). The dimensions of harmonization can include numerator, denominator, exclusions, calculation, and data source and collection instructions. The extent of harmonization depends on the relationship of the measures, the evidence for the specific measure focus, and differences in data sources. Value sets used in measures (especially eCQMs) should be harmonized when the intended meaning is the same. Harmonization of logic in eCQMs is beneficial when the data source in the EHR is the same. Harmonization can also mean adoption of the same standard(s) for different purposes such as use of standards for eCQMs and clinical decision support (CDS), for example Clinical Quality Language for logic expression in eCQMs and CDS.