Typological studies have tended to take for granted the default interpretation for English and imposed ‘simultaneity’ as the basic meaning of when -clauses for all languages. This in opposition to the approach taken in reference grammars, which generally report temporal linkage markers like when as encoding one or several meanings. Data from languages other than English show that comparative studies should also be open to the possibility that when -clauses do not always, or only, denote simultaneity. To support this claim and argue against the default interpretation of simultaneity, in this study I explore the range of temporal meanings of when -clauses across languages and provide evidence from Spanish and Yaqui corpora. Unlike English, corpus-based studies show that Spanish equivalent cuando -clauses equally introduce simultaneous and sequential readings, while Yaqui o-/kai -clauses predominantly express sequential meanings. Furthermore, a convenience sample of 28 unrelated languages reveals that, if there is a when -clause in a language, it can locate the event of the adverbial clause earlier, later, or around the same time as the main clause. The analysis of the semantic side of when -clauses demonstrates that there are language-specific tendencies regarding their temporal meanings. On these grounds, I propose that a better understanding of when -clauses can be arrived at by classifying them as ‘unspecific’ temporal clauses. This categorization would motivate a richer analysis of new data and a systematic comparison between unspecific, simultaneous and sequential clauses. Finally, I advance a four-way classification regarding general versus specific markers, and the temporal relations they encode, two of which account for most languages analyzed.