Abstract: The present invention provides antibodies that bind to the IL-3 receptor alpha subunit alpha (Il3R?) chain, and compositions comprising such antibodies. The present invention provides methods for inhibiting or reducing an IL3R?-expressing cell population, the methods comprising contacting a population of IL3R?-expressing cells (e.g., cancer cells and/or cancer stem cells) with an antibody that binds to IL3R?. The present invention also provides antibody conjugates comprising an antibody that binds to an IL3R? chain linked to a cytotoxic agent or anticellular agent and compositions comprising such conjugates. The present invention also provides methods for preventing, treating and/or managing a disorder associated with IL3R?-expressing cells (e.g., a hematological cancer), the methods comprising administering to a subject in need thereof an antibody that binds to IL3R?.