The effect of austenitization temperature, aging temperature, and, aging time on the development of precipitates in a novel maraging steel known as F1E was investigated. The investigation primarily employed small angle neutron scattering (SANS) coupled with thermal calculations, atom probe tomography (APT) and electron microscopy (SEM, STEM, TEM). This large scale study investigated austenitization temperatures of 825, 870 and 960 °C with aging of 0, 1, 2.5, 5, 7.5, 10 and 24 h conducted at 540 °C. For austenitization at 960 °C, aging at 520 °C and 560 °C was also conducted for the same aging times. This yielded 32 conditions where the size, shape and volume fraction of three different precipitates were determined, namely a pre-existing laves phase, a developing laves phase, and a developing β phase. Also observed in this study was a significant change in microstructure of the pre-existing laves precipitate as a result of aging time.