A series of space-time reactor kinetics experiments has been performed in the Solid Homogeneous Assembly. The ground rules were the following: 1. The cores were to be easy to model statically using few-group diffusion theory. 2. The dynamic behavior was to be one dimensional. 3. Significant flux tilt and delayed neutron flux tilt holdback effects were to be present. 4. The perturbation was to be essentially a negative step change in reactivity. 5. The flux distributions, absorber worths, and eigenvalue separation of each core were to be measurable in order to use this information to verify the core modeling process. The adequacy of few-group diffusion theory was checked using both one-dimen-sional multigroup (fast and thermal) and two-dimensional few-group transport theory calculations. The few-group diffusion theory model was solved in a cylindrical approximation using a finite difference code, and in correct 3D geometry using a synthesis code; the latter did an excellent job of predicting criticality and matching foil activation traverses made using the 55Mn (n, γ) thermal and 115In (n, n’) threshold reactions. The eigenvalue separation of each core was measured using both a static flux tilt method and a two-detector noise correlation method; the results agreed well with calculated values, indicating that these new experimental methods can provide an accurate determination of the eigenvalue separation of a core. The transient response of one of the cores to a step perturbation was compared to the response calculated using the space-time synthesis model. In general, it has been found that the transient response of the core can be predicted accurately provided that the core is well modeled statically, including the perturbation worth and the eigenvalue separation, and provided that the effective delayed neutron fraction is properly evaluated. This tends to verify the adequacy of existing methods for computing spatially dependent transients in cores describable by few-group diffusion theory.