This paper summarizes the results of several contamination analyses performed in support of Hubble Space Telescope (HST) system development. The discussion topics encompass several flight-phase operational and contamination events: prelaunch standby, on-orbit closed-door and open-door operations, HST interior outgassing, and ram-induced pressure rise in the Aft Shroud (AS) region. A number of refined analytical models (computer codes) have been used to carry out these analyses. The results indicate that the contaminant build-up during prelaunch and flight operations will be well within the HST contaminant allowable limits (about 50% the budget allocation). Specific findings are as follows: (a) no significant contamination of HST primary mirror (PM) and secondary mirror (SM) due to orbiter purge air will occur during prelaunch standby even with a worst-case scenario; (b) using a diffusion flux model and from available data on payload bay (PLB) sources, the deposition rates on the HST PM and SM have been predicted to be 0.4 angstrom/hr and 2.7 angstroms/hr, respectively, during on-orbit closed-door operations; (c) particulate contamination based on a scenario involving two astronauts during extravehicular activity (EVA) in conjunction with instrument change-out has been found to be negligibly small; (d) certain lubricating oils, if deposited on and not removed from HST interior surfaces, could cause significant contamination on HST critical optics; however, this potential contamination has been eliminated by HST thermal hakeout; (e) by utilizing a Monte Carlo model, the ram-induced pressure rise in the AS region has been predicted to be insignificant and would not violate the electric breakdown requirements.