This study investigates the Bass Diffusion model. Bass’ parameters of innovation (p) and imitation (q) help explain adoption, and the ratio of these parameters sheds insights on critical mass. This study compares the parameters p and q across 13 internet diffusion datasets in five tourism sectors across international, European and five national datasets. Information and communication technologies (ICTs) play an increasing role with tourists and tourism organisations. The data contain destination management organisations (Switzerland, Austria and Germany), tour operators (European and Swiss), accommodation providers (international chain hotels, Malaysian hotels, Swiss affiliated hotels and Swiss guest houses) and Swiss cable cars. This study also uses the Gamma/Shifted Gompertz model to incorporate heterogeneous adoption. Across the same datasets, tourism organisations showed heterogeneous adoption tendencies and the influence of critical mass. This exploratory research illustrates the usefulness of Bass’ parameters both as a foundation and to measure critical mass.