This paper outlines a series of studies on particulate and aggregative fluidization, starting from its first observation in the 1940's and culminating in its modeling, which both discriminates and reconciles these two types of fluidization, and in the experimental corroboration of the model with the use of supercritical carbon dioxide. These studies span three generations of efforts over the course of half a century and provide valuable knowledge in the interactive use of these two types of fluidization in developing new processes. The paper also outlines what to expect in extending this knowledge base into the next half century.