Road signs form a non-verbal semiotic system – by many encountered on a daily basis – that dictates the actions of the users of the road, in order to create a safe and efficient traffic environment. It is clear that road signs are not just ‘saying’ things but ‘doing’ something. This study examines the commanding and performative aspects of a set of Swedish road signs. The first part of the analysis is a detailed investigation of (the ‘grammar’ of) the warning sign, drawing on a theoretical framework of semiotics and Grice’s cooperative principle. The second part investigates the speech act status of warning signs, priority signs and prohibitory signs, by applying Searle’s taxonomy of illocutionary acts. Results show that the warning triangle is not arbitrary but iconically motivated, both in color and in form, and that the silhouettes vary on a number of parameters, including the perspective of their mapping, the degree of iconicity and the degree of ‘danger reality’. Warning signs, just like verbal warnings, are best categorized as directives, whereas priority and prohibitory signs, unlike verbal prohibitions, emerge as declarations. Ultimately, this raises questions regarding the limits of and the ‘translatability’ between verbal and non-verbal language.