Reminder / recall systems are an evidence-based strategy to increase immunization coverage among children and adolescents. To expand and enhance the recall function in New York City’s IIS, provider-based text message recall functionality was added to the IIS to alert parents of the vaccines their children were due to receive. Providers select their recall parameters and use a default message or create their own custom language for the texts. Prior to implementation, the program worked with a software vendor and mobile platform vendor to overcome the technical challenges of integrating the text message platform with the IIS. The program also worked with their legal team to determine permissible content for the text messages and the appropriate consent process for texting parents of patients. The program’s preliminary findings demonstrate greater patient vaccination following receipt of a recall text message.