Projective contents, which include presuppositional inferences and Potts's conventional implicatures, are contents that may project when a construction is embedded, as standardly identified by the FAMILY-OF-SENTENCES diagnostic. This article establishes distinctions among projective contents on the basis of a series of diagnostics, including a variant of the family-of-sentences diagnostic, that can be applied with linguistically untrained consultants in the field and the laboratory. These diagnostics are intended to serve as part of a toolkit for exploring projective contents across languages, thus allowing generalizations to be examined and validated crosslinguistically. We apply the diagnostics in two languages, focusing on Paraguayan Guaraní, and comparing the results to those for English. Our study of Paraguayan Guaraní is the first systematic exploration of projective content in a language other than English. Based on the application of our diagnostics to a wide range of constructions, four subclasses of projective contents emerge. The resulting taxonomy of projective content has strong implications for contemporary theories of projection, which were developed for the projective properties of particular subclasses and fail to generalize to the full set of projective contents.