Empirically based developmental and behavioral intervention programs targeting the core symptoms and language development in toddlers and preschool children with autism spectrum disorder Abstract. This systematic review summarizes findings of articles included in the German AWMF-S3 clinical guideline on early intervention in autism spectrum disorders (ASD). We present the current state-of the art of evidence-based interventions for toddlers and preschool-aged children with ASD, specifically targeting the core symptoms and language development. We included studies on manualized developmental and behavioral interventions for children with ASD aged <7 years according to DSM-III(R), DSM-IV(TR), DSM-5, and ICD-10. The publication dates ranged from 1 January 2011 to 31 August 2018 or as included in the NICE-children guidelines. Studies were included by an iterative hierarchy: systematic review > randomized-controlled trial > clinically controlled trial. Outcome measures were core ASD symptoms and precursor abilities, or language abilities. The interventions were collated by (1) frequency and (2) approach. The studies focused on low-intensive interventions targeting parental synchrony, the child's initiations, reciprocity, joint attention, play and imitation skills as well as comprehensive interventions. Improvement of core ASD symptoms regarding social communication was observed for low-intensive training of parental synchrony and child's reciprocity as well as for low-intensive comprehensive developmental interventions implementing natural-learning paradigms. High-frequency discrete trial interventions did not improve social communication. Language abilities improved by comprehensive interventions. In conclusion, intervention recommendations are summarized.