This paper is the latest contribution to a sequence of studies aiming to replace collapses resulting from measurements by spontaneous collapses [1-2]. The aim of Time Dependent Perturbation Theory (TDPT) is to calculate the transition probability between stationary states induced by a time dependent perturbation ([3], p. 168). Processes supposedly spontaneous, such as absorption and emission of radiation, radioactive decay and chemical reactions, involve transitions between stationary states. We have shown that in the framework of Orthodox Quantum Mechanics (OQM) transitions between stationary states require collapses, in turn requiring measurements. Hence, they cannot be considered spontaneous processes [1-2]. To solve this problem we assume that collapses necessary to yield transitions between stationary states are not the result of measurements but of a tendency of the system to jump into some states called preferred states. We suggest a modification of the formalism of OQM where the concept of preferred states plays a paramount role. The resulting theory is named Theory of Spontaneous Collapses Induced by a Time Dependent Perturbation (SCSS). Differing from other theories of spontaneous collapses [4], it is in compliance with the statistical meaning of conservation of energy.