Family-professional partnership is an essential component of the special education process for children with intellectual and/or developmental disabilities (IDD), including autism spectrum disorder (ASD). Latinx families face systemic barriers when participating in educational decision-making for their children with IDD. Few studies have examined the effectiveness of advocacy trainings among Latinx families of children with IDD, including ASD. The purpose of this pilot study was to examine the effectiveness and feasibility of the "Familias Incluidas en Recibiendo Mejor Educación Especial" (FIRME), an advocacy program for Latinx families of children with IDD, with respect to increasing special education knowledge, advocacy, empowerment, and receipt of services; and decreasing stress. After completing the FIRME program, participants demonstrated significantly increased: special education knowledge; advocacy; and empowerment.