Drawing upon a significant weight of empirical data, collected in the field, this thesis proposes a set of four spectrums of investment engaged in by cult media fans: the spectrum of financial investment; the spectrum of what is here termed 'participatory investment'; the spectrum of investment in the idea of textual authenticity; and the spectrum of multiple investments. The spectrum model allows the individual members of the research sample to be located within specific regions of each spectrum and correlations to be drawn between the distinct spectrums, in order for any patterns which emerge to be examined. The thesis also reviews a number of relevant theoretical concerns such as fan studies, ethnography and social psychology.