Investigations in Sex Estimation: A Comparison of Morphological and Metrical Methods is a collective comparison of the many morphological and metric methods currently used on adult and juvenile human remains. This single comprehensive resource for sex estimation in skeletal material includes discussion on the evolution of sexual dimorphism in modern humans, how sexual dimorphism manifests itself in those bones, the growth development in juveniles and how sexual dimorphism can be measured in their bones. Data is presented which contradicts previously held postulates and some different uses of sex estimation methods are suggested, such as using the grading system to assess evolutionary change in skeletons or grouping juveniles into smaller groups by age to better estimate sex. New insights are offered for future research from the presentation of case studies on gender and a comparison of the sex differences between two African-American collections which suggests a correlation between occupation and evolutionary change. To achieve the objective, data on 294 adults from four diverse collections of known sex are obtained using a total of 67 morphological and metric methods. An additional 23 morphological and metric methods used on juveniles, aged 0 to 18, from two of the collections. The methods are specific to either the cranium, mandible, pelvis, humerus or femur. The compilation of assessment of sex provides definitive answers on which type of method, morphological or metric, is more accurate, which morphological and metric methods are the most accurate, and which bones are more reliable to estimate sex especially in the absence of a pelvis. Investigations in Sex Estimation is intended to be used in the field and the laboratory for the identification of sex in human remains and aims to provide a wealth of data for future research in sexual dimorphic studies.