The intentions of this manual are to familiarize beginners with the process of bone marrow evaluation, to provide a succinct preparatory review of bone marrow pathology for the pathology and clinical hematology board examinations, to remediate practitioners whose knowledge of this field is not current, and to strengthen the skills of clinicians who apply bone marrow data to the care of their patients but who do not independently examine bone marrow specimens. The opening chapter, Bone Marrow Basics, is a review of information that most readers will have originally encountered in medical school. Taking nothing for granted, this material is included for the purpose of closing any possible gaps in the reader’s knowledge of elementary concepts, whether from primary omission or forgetfulness. The next chapter is an overview of the principles and utilities of special studies used for the genotyping and immunophenotyping of BM. It is vital that the reader have a general understanding of these tests, since genetics and antigen expression have now equaled or surpassed the importance of morphology for bone marrow evaluation. The vast majority of this manual is devoted to hematologic neoplasms in the bone marrow and closely follows the World Health Organization classification scheme that has become the international gold standard for the characterization of these disorders. This status has been achieved by integrating all relevant data into their disease definitions, including morphology, immunophenotype, genetics and clinical features. The final two chapters of this manual address specific approaches to evaluating bone marrow that is primarily or secondarily involved by lymphoma and cytopenias due to non-neoplastic causes. It is hoped that the impact of this manual will be some measure of demystification of the unfamiliar morphology, hi-tech ancillary studies and complex disease classification schemes that have made bone marrow pathology so intimidating to so many. Use this book as a starting-off point, and then go move some glass.