Material flammability is of great interest to engineers as they prepare to send items and human beings into space. Fire safety is important for both the safety of the crew and the spacecraft in which they travel. This thesis aims to give a better understanding of the flammability of specific materials in microgravity as oxygen levels and oxidizer flow speed change. This is especially significant as NASA is considering a change to higher oxygen percentages inside space vehicles, spacesuits, and space stations in the future. The materials tested in this thesis are commonly used in spacecraft to provide more pertinent information. Flame spread tests were performed on a variety of materials at specific oxygen concentrations as the opposed flow velocity is varied to study how oxygen concentration and flow velocity can impact the flammability of materials. The focus was on materials most commonly found in spacecraft including food and beverage packaging, clothing, escape suit material, and circuit board components. Tests were performed with the San Diego State University Narrow Channel Apparatus (NCA). Past studies involving the flame spread along Polymethylmethacrylate (PMMA) in the NCA have proved that the NCA is a functional microgravity simulator because it reduces the effects of buoyancy on flame propagation. Each material was tested at a thickness close to or exactly at its use thickness. Pressure was held at a constant 1 atm. Flame spread for each material was measured at 21% and 34% O2. Opposed flow velocity was varied from 2 cm/s to 120 cm/s to show how the flame spread velocity is correlated to opposed oxidizer flow velocity.