The Cold Spring Harbor Laboratory proposes to continue two courses in molecular biology, molecular genetics and biochemistry, whose methodologies are central for modern cancer research, to be held in 2023 - 2027. These short, intensive courses include Mouse Development, Stem Cells & Cancer (three weeks) and Chromatin, Epigenetics and Gene Expression (three weeks). Each course prepares the student to enter directly into research that makes use of advanced and/or specialized techniques and concepts that can be applied to studies of growth and regulation of normal eukaryotic cells and their oncogenic counterparts. Each course has a different emphasis and serves a different need. The course on Mouse Development, Stem Cells & Cancer trains scientists to study gene regulation and development in the context of the whole organism, as well as mouse models of human disease such as cancer. The course provides in intensive hands-on introduction to engineering of mouse models, stem cell technologies and tissue analyses. Lectures provide the conceptual basis for contemporary research in embryogenesis, organogenesis in development and disease, embryonic, adult and induced pluripotent stem cells and cancer biology. The course on Chromatin, Epigenetics and Gene Expression aims to expose students to a broad array of methodologies to study gene regulation, chromatin structure and epigenetics, including both well-developed and cutting-edge methods, such as ChIP, CRISPR and Next Generation Sequencing. The faculty is chosen on the basis of their contributions to and knowledge of the field covered in each course. The faculty invite lecturers who have made significant contributions to their fields and can provide up-to-the-minute reports on current research. The trainees range from graduate students to senior investigators who are chosen by the course faculty from a large number of applicants. Because of the short duration of the courses, senior, as well as junior, individuals can attend and receive an intense period of training in an environment remote from other demands on their on their time and attention. The courses provide an unusual opportunity for scientists to retrain in another specialty or to apply the work of a new field to their own research.