The goal of this proposal is to build on previous NSF supported research regarding the earliest stages of star formation; i.e. the initial fragmentation of giant clouds of molecular gas and the evolution of these fragments into dense cores that will eventually become newborn stars. The proposal aims to study these sites of star formation through a multi-wavelength campaign of observations from the radio to the infrared using a number of different ground-based and space-based facilities. The proposers will use these observations to test computational models of star formation and stellar evolution. The proposed new research will undertake a detailed systematic study of the physical, chemical, and kinematic structure of large populations of low-mass starless cores and high-mass starless clumps. For the high-mass starless clumps, the research will utilize the Bolocam Galactic Plane Survey (BGPS) previously completed by the PI to identify a statistically significant sample of high-mass starless clumps for more detailed study through observations with the IRAM, APEX, HHT, JVLA and ALMA. For the low-mass starless cores, the project will use radiation transfer modeling of the starless core population in molecular clouds to investigate the evolutionary phases of the cores and to determine the importance of magnetic fields during their evolution. The project will make use of low-mass starless core identifications from the space-based Herschel and ground-based SCUBA observatories. The project will perform new observations of these identifications with the 12m Arizona Radio Observatory and ALMA for comparison with the results from their radiative transfer models.