Abstract: As component of SFL textual metafunction and language resources to instantiate textual meaning, periodicity consists of Theme/New, hyperTheme/hyperNew, macroTheme/macroNew. Analysis of periodicity in texts shows that both recount and exposition make use of textual resources such as periodicity to scaffold texts into coherent generic structures. It is found the functions of the marked Themes in signaling generic stages or steps, hyperTheme and hyperNew in predicting information, as well as hyperNew and macroNew in summarizing and distilling information.