Structural priming is the phenomenon that speakers tend to re-employ structures they have lately understood or generated themselves. Most research on this topic is experimental and looked at within-language priming. However, there are now also much observational studies, an evolution that is inseparably linked to novel/larger corpora, novel statistical methodologies, and novel theoretical ideas. Second, there is an increasing body of research on cross-linguistic structural priming, albeit mainly experimental. These developments lead to a new possible research avenue: cross-linguistic priming on the basis of observational data. This study first resumes some basic studies of cross-linguistic priming, and then seeks out the historical evolution of observational studies of structural priming to exhibit how statistical and theoretical developments have molded research on priming in general and debate what such observational priming research has proposed to within-language priming research. It concludes with a debate of how this research can inform cross-linguistic priming.