The third edition of the Gross Motor Function Measure (GMFM-66 & GMFM-88) User's Manual has retained the information contained in the original 2002 and 2013 publications which included the conceptual background to the development of the GMFM, and the administration and scoring guidelines for people to be able to administer this clinical and research assessment tool appropriately. This includes information on the development and validation of two abbreviated methods of estimating GMFM-66 scores using the GMFM-66- Item sets (GMFM-66- IS) and the GMFM-66- B&C (Basal & Ceiling) and a chapter providing a longitudinal case illustration of how the measure and the short forms of the GMFM can be applied and interpreted in clinical practice.

The new edition includes information and an Appendix on the updated version of the Gross Motor Ability Estimator scoring program (GMAE-3), which is available through the GMFM App⁺ (see the CanChild website at (https://www.canchild.ca/en/shop/38-the-gross-motor-function-measure-app).

Changes from previous edition

• Includes information and an Appendix on the updated version of the Gross Motor Ability Estimator scoring program (GMAE-3), which is available through the GMFM App⁺ (see the CanChild website at www.canchild.ca).
• Chapter 8 which describes the ongoing work to continually update the GMFM tools has a section that addresses challenges that researchers and clinicians have had in using the tools and suggestions to use the measure appropriately.
• Updates on the Challenge module and the Quality FM, translations, and the use of the GMFM in populations other than cerebral palsy and Down Syndrome have been included.
• New Appendix introducing the Gross Motor Family Report (GM-FR)
• Updates to chapter 8 including new content covering additional translations of GMFM, and updates to development work of GMFM and applications in other childhood diseases.