Background:Child well-being is an important outcome and has received attention from researchers for decades. Until recently, there has been difficulty in drawing conclusions from these studies because of the wide variety of measures used.

Objective:This systematic review aims to summarize and assess the measurement properties of existing child well-being instruments presented in the literature.

Methods:This systematic review will focus on studies that evaluated the psychometric properties of instruments to measure the well-being of children ages two to seven. The search strategy will aim to locate studies in the English language completed from 2000 to 2023. The databases to be searched include MEDLINE via PubMed, CINAHL Plus, and Psychology & Behavioral Sciences Collection via EBSCOhost. Proquest Dissertations and Theses, Google Scholar, and Research Gate will be used to search unpublished studies. Following the search, all identified citations will be collated in Mendeley. The full text of selected citations will be uploaded to JBI-SUMARI, assessed in detail against the inclusion criteria, and critically appraised using the COSMIN Risk of Bias checklist by two independent reviewers. Data will be extracted using JBI-SUMARI by one reviewer and verified by another. Findings will be reported using a narrative synthesis and tables. If possible, a meta-analysis will be performed. The evidence for each measurement property for each instrument will be compared against acknowledged standards for appropriate measurement characteristics using the COSMIN-proposed "criteria for good measurement properties."

Expected Results:This systematic review will provide further evidence regarding the measurement properties of instruments used to measure the well-being of children, specifically in the early years. The findings of this study will be disseminated through a conference presentation and publication in a peer-reviewed journal

PROSPERO registration number:CRD4202342T8953