Star formation commonly results in the production of star clusters. In recent years, observations with the Hubble Space Telescope have led to the discovery of young, massive star clusters in nearby galaxies, constituting a new class that may bridge the gap between open and globular clusters. In this thesis, I present observational studies focused on understanding the properties of young, massive cluster (YMC) populations across a range of galactic environments. Using multiwavelength HST data from the Snapshot Hubble U-band Cluster Survey, I select a high-confidence sample of YMCs in the spiral galaxy NGC 2997 and perform photometry. I characterize the physical properties of the YMC population, including determining the luminosity and mass functions, age distribution, and efficiency of cluster formation. This work helps to establish that in relatively quiescent spiral galaxies, YMCs tend to form with efficiencies of ~10%, and can survive for at least a few hundred Myr. I then present a study of star formation associated with giant gas filaments surrounding NGC 1275, the central galaxy in the Perseus galaxy cluster. I identify a population of YMCs embedded in "streaks" of stars using far-ultraviolet and optical data from HST. These objects may form when the galactic-scale gas filaments slow their expansion and become gravitationally unstable in the outer regions of the galaxy. This work shows that cluster formation can proceed relatively normally in unusual environments, and may form isolated clusters in the outskirts of galaxies. Finally, I focus on the structural properties of YMC populations in two studies. In the first, I measure the effective (half-light) radii, core radii, and light profiles of ~200 YMCs in seven adjacent HST fields on the spiral galaxy M83. In the second, I build upon the findings in the first using YMC samples from two spiral galaxies in the Legacy Extragalactic UV Survey, NGC 628 and NGC 1313. These studies imply that YMCs emerge from early evolution with similar radii, typically 2-3 pc, and are not strongly affected by their local environment.