The effects of a compartment fire on a real fire ground is seldom isolated to a single room. In Sweden, for example, over one-third of fire fatalities in apartments are in a room other than the origin room, but in the same apartment (Johansson, 2015). Still, much of the scientific testing and modeling of compartment fires involves a solitary room. This dissertation studies the fire dynamics of multi-room compartment fires by exploring the room of origin as well as adjacent rooms. A multi-room test presents greater potential variability than an isolated compartment fire test. This work included 52 small-scale and 45 full-scale three-room apartment building tests with different ventilation scenarios to evaluate the repeatability of the testing. The paper also discusses different categories of fires in buildings, including structural element, compartment, and large enclosure fires and presents analytical methods for estimating the fire characteristics in multi-room fires. This paper provides insight into fire behavior that can be used to make fire operations more effective and safe.