Purpose: Obtaining information on both languages of English language learners for assessment can be a challenge in a multilingual context. It is often difficult or impossible to observe a child's first language directly due to the absence of resources available in every language spoken. The objectives of this study were (1) to develop a parent questionnaire on the first language development of English language learners that is not specific to a particular language/cultural group: the Alberta Language and Development Questionnaire (ALDeQ), and (2) to test how well scores on the ALDeQ differentiated between English language learners with typical development and those with language impairment. Method: Participants were 139 typically developing children and 29 children with language impairment, aged 69 months with 18 months of exposure to English through preschool or school, on average. The ALDeQ consists of four sections: early milestones, current first language abilities, behaviour patterns and activity preferences, and family history. ALDeQ total scores are proportions calculated across all sections. Results: t-test analyses revealed robust between-group differences for ALDeQ total scores, and for each section score, with medium to very large effect sizes. Linear discriminant function analysis showed the ALDeQ total scores to be a significant and moderate discriminator between the typically developing and language impaired group, but with better specificity than sensitivity. The early milestones section scores emerged as the strongest discriminator among the four section scores. Parent responses showed that both the typically developing and language-impaired groups included children experiencing first language loss, but nevertheless, the current first language abilities section was the second strongest between-group discriminator. Conclusion: The ALDeQ would be useful to speech-language pathologists for obtaining information on English language learners' first language development, in particular where the first language cannot be examined directly. The information provided by the ALDeQ could be used in conjunction with other measures in order to identify children with language impairment among English language learners. The complete ALDeQ and score interpretation information are given in Appendix A. Learning outcomes: Readers will (1) have a general understanding of how parent report could be useful for assessment in a multilingual context; (2) be aware of how first language loss in minority language children could impact assessment, and (3) have specific knowledge of a particular parent questionnaire and how it can be used to assist in identifying English language learners with language delay/impairment. (Contains 1 figure and 5 tables.)