Infants with older siblings having Autism Spectrum Disorders (ASD) are at genetically increased risk for showing characteristics of ASD in the first 2 years of life. Parents, who already have at least one child with ASD, may closely monitor their later born children and implement interventions as soon as the children begin to show what the parents believe is aberrant behavior or development that may be early stages of ASD. To date, no study has examined the number and types of services and interventions these parents access for their at‐risk infants. Using a Service and Intervention Questionnaire developed for this study, we interviewed 23 parents involved in a larger prospective study of genetically at‐risk infants who reported developmental and/or behavior problems in their at‐risk infants. Parents reported utilizing a mean of 1.83 and 7.26 services and/or interventions for their at‐risk infants and older children with ASD, respectively. Two‐thirds of the interventions received by the infants were also given to their older affected siblings. The interventions included empirically validated approaches (e.g., early intensive behavioral intervention), professional services (speech–language therapy, occupational therapy), and non‐validated treatments (e.g., diet and vitamin therapies). Overall, 81 non‐validated and 18 validated interventions were used. On a Likert‐type rating scale, parents reported being involved and satisfied with what they generally thought were effective services. They felt more involved and satisfied with ABA, and felt it was more effective than non‐validated interventions. The findings suggest that parents with infants at‐risk for ASD and an older affected child will access a variety of autism services for both children, but the parents will implement primarily non‐validated interventions. Parent education is recommended to help parents make informed treatment decisions for their children. Copyright © 2009 John Wiley & Sons, Ltd.