Analysis suggests that progress in conservation of plastics objects and artworks can be described by a series of overlapping mesocycles. Focus has been placed for periods of 5-10 years each on determining the degradation pathways in the 1990s, developing strategies to inhibit those pathways from the late 1990s and, since 2006 on actively stabilizing and treating the symptoms of degradation. The primary driving forces behind the direction and rate of progress within each of these 3 mesocycles have been different and specific. The controlling factor in understanding degradation pathways for heritage plastics has been the origin of the data describing lifetimes. By contrast, mesocycles in developing suitable storage and display microclimates for plastics have mirrored preventive conservation practices for natural polymeric materials. The rate of the third mesocycle, interventive conservation, has been driven by the need to balance the requirements for reversibility in conservation practices with the artist’s intent and significance. Developments within each of the three mesocycles from the 1990s to date are discussed in this article. Environmental science and toxicology of waste plastics offer a novel source of information about real time degradation in terrestrial and marine microenvironments that seems likely to contribute to the conservation of similar materials in contemporary artworks.