CQL is a Health Level Seven International® (HL7®) authoring language standard that is intended to be human readable. It is part of the harmonization effort to align specification development for quality measures, including electronic clinical quality measures (eCQMs) and clinical decision support (CDS) artifacts. CQL provides the ability to express human-readable logic structured sufficiently for processing a query electronically. CQL is the expression logic used in Health Quality Measure Format (HQMF). Measure authors with access to the Measure Authoring Development Integrated Envirnoment (MADiE) can use the tool to author measures using CQL. Visit the MADiE webpage for more information.
CQL allows for a more modular, flexible, and robust expression of the logic. It allows sharing of logic between measures and clinical decision support.
Latest Versions
- The CQL standards are located on the HL7 Website: CQL Specification.
- The latest version of CQL is v1.5.3: Current Official Published Version - Normative Release 1 (mixed Normative/Trial-use content), based on Fast Healthcare Interoperability Resources® R4.
- Find the QDM versions for use with Clinical Quality Language (CQL) on the QDM page.
- See the QDM-based CQL Style Guide (v9) for calendar year 2026 reporting.
CQL Archived Resources
- CQL Style Guide (v8) aligns with the CQL expression style of eCQMs using CQL for calendar year 2025 reporting.
- CQL Style Guide (v7) aligns with the CQL expression style of eCQMs using CQL for calendar year 2024 reporting.
- CQL Style Guide (v6) aligns with the CQL expression style of eCQMs using CQL for calendar year 2023 reporting.
- CQL Style Guide (v5) aligns with the CQL expression style of eCQMs using CQL for calendar year 2022 reporting.
- CQL Style Guide (v4) aligns with the CQL expression style of eCQMs using CQL for calendar year 2021 reporting.
- CQL Style Guide (v3) aligns with the CQL expression style of eCQMs using CQL for calendar year 2020 reporting.
- CQL Style Guide (v2) aligns with the CQL expression style of eCQMs using CQL for calendar year 2019 reporting.
Explore these resources to get an overview of CQL and learn how to implement CQL from experts.
- Learn more about the fundamentals of CQL and why it is important on the CQL Education tab. Also, find past presentations and webinars for the various audiences who might use CQL.
- Attend an upcoming Cooking with CQL, Quality Data Model (QDM), and Fast Healthcare Interoperability Resources® (FHIR®) webinar. The sessions feature open discussion from subject matter experts on the Measure Authoring Tool (MAT), show how to express measures using CQL, and review questions. Visit the Electronic Clinical Quality Improvement (eCQI) Calendar to find registration information.
- Get a good start with CQL by visiting the CQL Frequently Asked Questions (FAQs) page to review common questions and answers.
- Visit the Connect tab to find out how to connect to various CQL resources and register for upcoming CQL sessions.
CQL Tools for Implementers
- Visit the GitHub Tools repository to find tools in support of CQL, such as the CQL-to-Expression Logical Model (ELM) Translator used by implementation vendors.
- Explore the eCQI Tools & Key Resources page for a complete list of tools and resources used with electronic clinical quality measures (eCQMs) and eCQI.
- CQL-to-ELM Translator Reference Implementation
The Health Level Seven International® (HL7®) CQL specification defines both a high-level, author-friendly syntax for expressing clinical knowledge, and a machine-friendly, syntax-independent canonical representation of clinical knowledge called ELM. The design of the high-level ELM syntax is to support measure and decision support authors, while the design of the canonical representation is to support point-to-point sharing and machine processing applications.
CQL Resources for Authors
- CQL Formatting and Usage Wiki
- Visit the wiki, which serves as a collaborative workspace for the development of CQL formatting conventions and usage patterns for the representation of logic within quality measures. A selection of resources found on the wiki are
- Visit the HL7 Website to access the CQL Specification.
- QDM-based CQL Style Guide (v9)
QDM-based CQL Style Guide (v9) provides guidance to measure developers for authoring measure expressions and using functions, libraries, and definitions for calendar year 2026 reporting. Modifications to the QDM-based CQL Style Guide include references to the HL7 CQL standard, the HL7 CQL-based Health Quality Measure Format (HQMF) Implementation Guide, and input from standards owners and measure developers to refine CQL expression. The purpose of the QDM-based CQL Style Guide is to standardize the expression of measure concepts across eCQMs and define a uniform “look and feel” to eCQM logic using CQL. The QDM-based CQL Style Guide focuses on a set of common best practices implemented across CQL-based eCQMs in CMS quality reporting programs. The QDM-based CQL Style Guide also promotes the use of consistent language within the framework of CQL, including libraries, aliases, definitions, functions, and guidance on other conventions, such as operator precedence. Measure stewards and measure developers who are developing or specifying eCQMs for future inclusion in CMS programs should align with these best practices.
CQL Overview
- CQL 1.5 and Quality Data Model (QDM) v5.6 Overview Slides - September 2, 2021
Teach Me CQL Video Series (Video shorts can be viewed in any order)
- Day of v Date From and Timing Comparisons - YouTube Video Short - August 2024
- Fluent Functions - YouTube Video Short - July 2024
- Hospitalization with Observation - YouTube Video Short - July 2024
- AND OR Precedence - YouTube Video Short - July 2023
- Open and Closed Parentheses - YouTube Video Short - July 2023
- Choice Types - YouTube Video Short - June 2023
- Birth Date - YouTube Video Short - June 2023
- Latest, LatestOf, Earliest, EarliestOf, HasStart, HasEnd - YouTube Video Short - August 2022
- Coalesce - YouTube Video Short - August 2022
- Normalize Interval - YouTube Video Short - July 2022
- Time Zone Considerations - YouTube Video Short - July 2022
Cooking with CQL Sessions
- Cooking with CQL, QDM, and FHIR® Monthly Webinar Slides - Updated September 2022
- Visit the Cooking with CQL Examples GitHub page to review agendas, examples, and recordings from the most recent Cooking with CQL sessions.
- Visit the Cooking with CQL Q&A All Categories GitHub page to review all the questions and answers from the past Cooking with CQL sessions.
To review common questions and answers about CQL, visit the eCQI Center's FAQs page and expand the Clinical Quality Language topic.
Get Connected
- Visit the CQL Formatting and Usage Wiki.
- The Wiki serves as a collaborative workspace for the development of CQL formatting conventions and usage patterns for the representation of logic within electronic clinical quality measures (eCQMs). All users have edit rights to submit edits, and add comments and concerns. Items on the Wiki are a work in progress and subject to change.
- Join the CQL Technical Chat Discussion. (Log in or sign up for a free account.)
- Participate in an upcoming Health Level Seven International® (HL7®) Clinical Decision Support (CDS) Work Group call.
- This Work Group discusses CQL in the HL7 Clinical Quality Framework-on-Fast Healthcare Interoperability Resources® (CQF-on-FHIR).
- Add to or review the CQL Mixed Normative / Trial Use Specification comments on the HL7 Jira (search for CQL to view the comment page for the most current version of the standard).
- Submit general information questions about CQL to ecqm@icf.com.
- Submit feedback on CQL issues, comments, and technical questions to the ONC Jira CQL Issue Tracker.