This paper uses van Leeuwen’s (2008. Discourse and practice: New tools from critical discourse analysis. Oxford: Oxford University Press) Authority Legitimation framework to examine government posters published in the 1950s–1980s in Hong Kong, which serve as a means of shaping public opinion and legitimate social action. Martin and White’s (2005. The language of evaluation: Appraisal in english. London: Palgrave Macmillan) Appraisal framework is also applied to provide the study with relevant analytical tools by which to construct evaluatively coherent authorial reading positions propagated by the government in the posters as well as aligning viewers with these desired positions. The government posters being studied are concerned with various aspects of social practices in the domain of public health communication. This paper argues that the representations of these social practices are realized as texts – both visual and verbal – in the posters, as part of a broader recontextualization process where legitimate ways of doing things as stipulated in the government guidelines are recontextualized in these posters and conveyed to members of the public. The aim is two-fold: (1) to provide a systematic analysis of how visual and verbal resources construe evaluation in the government posters and the consequent legitimation discourse as viewers are being persuaded to align with legitimate social practices; (2) to highlight various forms of legitimation, namely, role model authority legitimation, impersonal authority legitimation, and conformity authority legitimation, that are realized in these posters through visual-verbal articulation.