This study examined the content validity and preliminary structural validity of the Sensory Integration Infant Routines Questionnaire (SIIRQ), a tool designed to screen for behaviors reflecting possible sensory integration concerns in children aged between 8 and 24 months. This study included two main phases. In phase 1, we examined content validity through cognitive interviews with experts and caregivers. In phase 2, we explored preliminary structural validity through item discrimination, analyzing the dispersion of responses within the 4-point Likert scale. Preliminary internal consistency using Cronbach's alpha was also explored. Experts demonstrated a high degree of agreement, and their input was useful in establishing items to help identify sensory integration vulnerabilities within daily routines. Caregivers unanimously reported that the instrument and the instructions were easy-to-understand. The questionnaire item responses demonstrated good dispersion and appear to capture behaviors that are consistent with sensory integration concerns in daily routines. The homogeneity of the items within each dimension (Cronbach's alpha) ranged from 0.60 to 0.87. The final version of the questionnaire includes 102 items aimed at detecting sensory integration vulnerabilities within the child's daily routines, in accordance with currently accepted models of early intervention.