Estimating the age at death in the adult skeleton is problematic owing to the biological variability in morphological age indicators and the differential response to environmental factors over an individual's life. It is becoming increasingly important for anthropologists to improve age estimates through the use of multiple age indicators and various modalities of assessment (e.g., macroscopic, microscopic, and radiological). Lack of instructional texts describing how to prepare histological samples and evaluate bone under the microscope has been a restricting factor in the widespread use of current histological methods within the field of forensic anthropology. The limited use of histological methods for age estimation often lies in the misunderstanding that the preparation and evaluation of cortical bone thin sections is a highly technical and an expensive endeavor. Like any method of age estimation, the researcher/practitioner must be guided through the analytical process to ensure reliable and repeatable results. This chapter provides a step-by-step instructional guide in the preparation and evaluation of histological samples removed from the sixth rib for histological age estimation.