Sex and age identification of human skeletal remains is essential in forensic anthropology, bioarchaeology and palaeodemography, and estimations rely on the use of proven methods. Many methods exist and are generally applied to skeletons from all time periods and geographic locations, despite studies suggesting that there are differences in the expression of traits characteristic of males and females and that ageing rates vary within and between populations. The aim of this project was to study variation in ageing and sexual dimorphism in six documented collections from different geographic locations and/or time periods. Age and sex methods were tested on adult skeletal remains dating from the 17th to 20th century from Canada, England, South Africa, and Portugal. Ageing methods used were focused on the fourth rib’s sternal end, cranial sutures, pubic symphysis and auricular surface. A more subjective age estimate for each individual was also produced, using informal skeletal age indicators alongside formal methods. Sex determinations were based on pelvic and skull morphology, and metrical analysis. Differences were found between some collections in terms of the distribution of age phases and mean ages per phase. Similarly, distributions of sexually dimorphic traits were found to differ between some of the collections. In terms of overall age estimates, the subjective age estimates were significantly better than estimates based only on formal ageing methods, and intraobserver error tests suggest that user experience was important. The magnitude of such differences and their implications for bioarchaeology, forensic anthropology and palaeodemography are discussed.