Ages of attainment for early gross motor milestones have been widely studied, but definitions and measurement methods have varied greatly. Since delays in motor milestones have been used extensively as one of the earliest indicators of atypical development, it is imperative to establish a universal understanding of the methods and results reported on motor milestones in typically developing children. Therefore, the primary aim of this scoping review is to provide an overview of recent studies reporting ages of onset for independent sitting and walking in typically developing children worldwide; this will be achieved by summarising how these milestones have been operationalised and evaluated, the samples from whom these data have been drawn, and the reported ages of acquisition.

To meet inclusion criteria, articles must: be original research papers published in any language since 2003, contain a sample of typically developing children and report actual ages of onset for independent sitting and/or walking. To conduct this scoping review, the Joanna Briggs Institute methodological framework will be used. Search terms will include variations of the following concepts: acquisition of motor milestone (independent sitting and/or walking), age of onset, infancy. Six databases (CINAHL Plus, Embase, PsycNet: PsycINFO & PsycArticles, PubMed, Scopus, Web of Science: Core Collection) will be searched. Records from these databases will be screened for eligibility. Two people will independently review each record during title and abstract screening, and three people will independently screen full texts and extract data. Results will be displayed in tables, graphs and narrative summaries in the scoping review.

As the review will only include previously published data, ethics approval is not required. Findings will be shared at scientific conferences and in a peer-reviewed journal.