As delays or disorders in early language and communication are the most prevalent symptom in children with disabilities, early screening is crucial to promote prevention, early diagnosis, and intervention. However, to the best of our knowledge, no screening tool is available for the joint assessment of early language and social communication skills in European Portuguese (EP)-learning children, which is critical for screening, monitoring and enrolment in appropriate early intervention services. (1) To adapt and validate the EP version of the Communication and Symbolic Behaviour Scales Developmental Profile™ (CSBS DP™) Infant-Toddler Checklist, a parental report for the screening of early language and social communication skills. (2) To conduct a cross-cultural comparison between the EP adaptation and the original US version. A total of 611 EP-learning children (ages 6-24 months) were assessed on the CSBS DP Infant-Toddler Checklist. Normative data, psychometric characteristics (i.e., internal consistency and test-retest reliability), and cross-cultural comparison between the EP and the original version were explored. Internal consistency ranged from good to excellent and the test-retest reliability was excellent. The performance of the EP and US samples matched on almost all scores. However, EP children performed significantly better than their American peers in the Social compositive at 22 months and in the Symbolic composite at 20 months. No further differences were found. These findings showed that the EP CSBS DP Infant-Toddler Checklist seems to be a reliable screening tool of communicative and symbolic behaviours for EP-learning children, which can be particularly relevant for decision-making in clinical practice. What is already known on the subject Early communication skills are known to be related to later language outcomes. Thus, screening tools for the early identification of children at risk for language and communication impairments, which may lead to monitoring and early intervention, have the potential to promote better outcomes. However, to the best of our knowledge, no screening tool is available for the assessment of early communication abilities in EP-learning children. What this paper adds to existing knowledge This study adapted and validated the EP CSBS DP Infant-Toddler Checklist, the first published parental report checklist for the assessment of early communication skills in EP. It described the psychometric characteristics of the adapted checklist, summarized the newly available normative data for EP-learning infants and toddlers, and compared the performance of EP-learning children with the original standardization sample reported for American English. The results demonstrated that this tool is a reliable instrument for the early screening of language, communicative and symbolic behaviours for EP-learning children between 6 and 24 months of age. What are the potential or actual clinical implications of this work? Given that early screening is crucial to promote prevention, early diagnosis and intervention, the availability of this tool is particularly relevant for children monitoring and their enrolment in appropriate early intervention services, helping decision-making in clinical practice, in line with current guidelines regarding early monitoring and intervention to promote and support better outcomes. Thus, the tool and related normative data will be useful for paediatricians, family doctors, primary healthcare providers, developmental psychologists and speech-language therapists, among other professionals in the healthcare and educational fields, concerned with speech, language, and communication development and impairments.