Appointment reminders help parents deal with complex immunization schedules. Preferred content of text-message reminders has been identified for English-speakers. Spanish-speaking parents of children under three years old were recruited to develop Spanish text-message immunization reminders. Structured interviews included questions about demographic characteristics, use of technology, and willingness to receive text reminders. Each participant was assigned to one user-centered design (UCD) test: card sort, needs analysis or comprehension testing. Respondents (N=54) were female (70%) and averaged 27 years of age (SD=7). A card sort of 20 immunization-related statements resulted in identification of seven pieces of critical information, which were compiled into eight example texts. These texts were ranked in the needs assessment and the top two were assessed for comprehension. All participants were able to understand the content and describe intention to act. Utilizing UCD testing, Spanish-speakers identified short, specific text content that differed from preferred content of English-speaking parents.