Purpose: To investigate feasibility and reliability of functional mobility measures in children with Cri du Chat syndrome (CdCS). Methods: Nine children with CdCS and 9 children with typical development (TD) completed the Timed Up and Go, 5 times sit-to-stand test, Timed Floor to Stand, and 4 Square Step Test. Feasibility was determined using testing time and need for modifications. Intraclass correlation coefficients were calculated for intrarater and interrater reliability. Results: Children with CdCS required modifications to complete all tests. One child with CdCS completed the 4 Square Step Test. Good reliability was found for both groups. Conclusions: The Timed Up and Go, 5 times sit-to-stand test, and Timed Floor to Stand are feasible and reliable tools for children with TD between ages of 5 and 15 years; however, may require modifications to the protocols to be feasible in children with CdCS. The 4 Square Step Test is not a feasible tool for children with CdCS.