International School of Brooklyn project, launched by Dr. Habiba Boumlik in March 2003, has grown from an idea supported by a group of 10 people to a grassroots, parent-led movement with over 100 Brooklyn and NYC families committed to the founding of ISB.

During Fall 2003 and Winter 2004, Dr. Boumlik, Rebecca Skinner and other committed parents held open meetings in Park Slope, Fort Greene and Boerum Hill, surveyed interested families in order to identify the needs of the community, and set in motion the process of incorporating as a non-profit school.
Of the more than 100 families surveyed, with children ranging in age from newborn to 9 years old, 58% were interested in French, 29% in Spanish, and 13% in German. While many of these families speak English at home, other native languages include French, Spanish, German, Creole, Portuguese, Russian, Arabic, Dutch, Catalan, Korean, Serbo-Croatian, Hindi, Italian, Latin and Japanese.

In March 2004, the Friends of the International School of Brooklyn was created as a not-for-profit corporation organized to undertake preliminary activities necessary for the formation and chartering of ISB. In September 2004, ISB received its operational charter from the New York State Department of Education and spent the 2004-2005 school year piloting language immersion playgroups in Park Slope, Cobble Hill and Brooklyn Heights and laying the foundation for the preschool opening. In September 2005, ISB launched the preschool program with 16 students in its inaugural class.

In September 2007, ISB expanded to 65 students in Nursery through 1st Grade, moving to a larger facility in Prospect Heights. ISB continued to grow through 3rd Grade at this location. In September 2010, ISB moved to a full school building in Carroll Gardens, welcoming 165 students in Nursery through 4th Grade. Currently, plans are in place to open a middle school in 2012.