Analyses are made of technological progress, using four technical areas as case studies. The progress in an area is measured by the cumulative number of "valuable events" in that area, where an event is defined as a new idea, a new structure, a new material, or anything new that is reported, developed, or invented. The four areas studied are (1 ) transverse mode stabilization structures of the semiconductor laser, (2) excimer laser gas materials, (3) solid-state laser materials, and (4) optical storage media. It is found that the rates of change in the cumulative event numbers are well described by the Verhulst equation and that progress time histories are well represented by sequences of logistic curves. It is found that most technological progress is characterized by a fast growth period of about 10 years with a time constant of 1 to 3 years. This first growth phase is followed either by saturation or by a smaller secondary growth phase.