Dr. Dennis Mileti devoted his career to the study of public warnings disseminated through mass media, word of mouth, and, later, mobile technologies. To date, research on mobile public warnings has focused on standardized elements of messages (e.g., the common alerting protocol). During this same period, however, a variety of private, public, and governmental organizations have adopted mobile alert technologies to disseminate a diverse variety of free-form (nonstandardized) messages. We investigated how the evidence-based guidance developed for mobile public warnings applies to this broader class of free-form mobile alerts and warnings (FMAWs). This study reports an experimental comparison of US residents’ (N=299) reactions to notional free-form mobile messages about a safety risk. Experimental conditions compared messages that included safety instructions, ways to seek additional information, expressions of empathy, and emphasizing choice (“choice forward”). Results indicated that message efficacy was greater for FMAWs that gave safety instructions rather than just notifications. Choice-forward FMAWs produced both message efficacy and safety efficacy, or confidence that the person could make a good safety decision for the situation. Application: When the location, timing, and severity of an emergent risk are ambiguous, or when for public safety organizations, they have not yet reached a threshold appropriate for wireless emergency alert messages, a free-form message disseminated through mobile technologies or social media could use choice-forward language and links to more detailed information about possible self-protective action to facilitate just-in-time pre-event education and preparedness.