Jerome J. La Rosa became a member of the PML Radioactivity Group (RG) in 2004. Previously he had worked for the International Atomic Energy Agency (IAEA) at both its Seibersdorf, Austria (terrestrial environment) and Monaco (marine environment) laboratories between 1987 and 2004 with an 8-month interim period as a guest scientist at the European Union’s Joint Research Centre IRMM in Geel, Belgium. His professional interests include radiochemical measurement of radionuclides in environmental matrices with special emphasis on destructive analyses using sample decomposition, dissolution and chemical separation followed by alpha spectrometry (e.g., actinides) and beta particle counting (e.g., Sr-90/Y-90). This expertise is applied in the development and characterization of complex reference materials (e.g., soils, sediments, biological materials) for their radionuclide concentrations. When the material is under development by an outside organization, NIST’s RG is often invited to participate in an international inter-comparison exercise aimed at establishing the radionuclide concentrations by consensus approach. Other applications of his experience include the preparation of performance testing (PT) materials to evaluate the measurement capabilities of laboratories with critical assessment of their traceability to NIST in programs such as the NIST Radiochemistry Inter-comparison Program (NRIP). Consultation on chemical/radiochemical problems with colleagues both within and outside of the RG provides a stimulating work atmosphere in which to share experiences and to discover opportunities for exploring new ideas in advancing NIST’s mission.