This study examined the variability and fragility of post-modern apprenticeship of clinical and biomedical scientists, different experiences of the fortunate and the unsupported, and problems facing professional associations trying to support their members professional learning. Focus was on Medical Laboratory Scientific Officers (MLSOs) working in the National Health Service in the United Kingdom. Methods for data collection were 9 surveys covering over 5,000 scientists, 260 interviews, 10 case studies of local/regional training schemes, and 30 meetings with professional groups. Findings related to the work environment identified the changing nature of scientific work in hospitals, changes in the pattern of who does the work, changes to the ways in which scientific services are facilitated and organized, and consequences for staffing levels and workloads. Findings related to training indicated funding lasted for 2-3 years, with some flexibility in length of training; MLSOs used logbooks developed by the Registration Board to specify training required in each discipline and a common core; arrangements for supervision appeared sufficient; feedback was inadequate; 18 learning processes were identified; former trainees positively endorsed training quality; and designated trainees said their academic and laboratory training were very good or good. Several issues were identified: quality assurance, professionalizing the training function, future of training for the health scientist professions, and training fit for purpose. (Contains 13 references.) (YLB)