Guided by Bronfenbrenner's bio-ecological theory of human development and Moll's theory of funds of knowledge, the aim of this qualitative study was to examine the beliefs of parents and early childhood teachers on (a) the language development of Spanish-speaking preschool dual language learners (DLLs) and (b) how they can collaborate to support DLLs. Parents (n = 14) and early childhood teachers (n = 17) of Spanish-speaking DLLs participated in focus groups and interviews. Data were analysed using the consensual qualitative research method [Hill, C., Thompson, B., & Williams, E. (1997). A guide to conducting consensual qualitative research. The Counseling Psychologist, 25, 517-572]. Nine themes emerged about parents' and teachers' beliefs about DLLs' language development, and three themes emerged about parent-teacher collaboration. Findings indicate several practice implications, such as a need for education about second language acquisition and development of sustainable models to form collaborative partnerships between parents and teachers. (author abstract)