The article describes the personnel filling of the Soviet atomic project at various stages of its implementation. The focus is on the scientists, technologists, engineers, technicians and workers of the research and industrial «atomic» objects. The special contingent and military  builders  used in construction have been taken out of the framework of the analysis: their involvement was based on other principles and should be studied separately. The study is based on declassified archival materials, published documents and memoirs. For the first time in historiography, the author shows the dynamics of the project’s personnel recruitment – from unsuccessful efforts to catch some necessary specialists to the mass replenishment of highly qualified personnel. It is established that such a process (especially at the stages of the project formation) was difficult and ambiguous. The solution of the personnel issue depended on the degree of state interest in the project and its status. Systematic and largescale personnel filling of the project became feasible only in connection with its activation in 1945 and the emergence of special (non-governmental and inter-ministerial) administrative bodies. Contrary to the opinions prevailing in the literature about the illimitable possibilities of “atomic” mobilization, its limits are shown both in cases of personified and collective recruitment.