This protocol presents the planned and upcoming work for a systematic review of the topic positive factors facilitating cooperation between early childhood education and care (ECEC) institutions, and multilingual parents. The number of children with a foreign background, both in Scandinavia and internationally, has increased during recent decades. These children are often exposed to more than one language on a daily basis. Earlier research has established that collaboration between ECEC institutions and parents is a vital factor in children’s development, learning, and school success. This is especially the case for multilingual children with a foreign background. This protocol discusses research-based knowledge in relation to this collaboration, and identifies a knowledge gap regarding up-to-date research on the positive factors enabling collaboration between ECEC institutions and multilingual parents. The aim of the planned systematic review is to contribute a scientifically based overview of knowledge about the positive factors facilitating collaboration between ECEC institutions and multilingual parents. The choice of methods for conducting this systematic review is stated and described in the presented protocol.