A method of generating a population of ectodermal or mesodermal/endodermal progenitor cells comprising: (a) dissociating mammalian pluripotent stem cells into clusters or single cells; (b) (i) for ectodermal progenitor cells, culturing the dissociated cells from a) in suspension and/or in a microwell device in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 260 to 280 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or adhering the dissociated cells from a) and culturing in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 270-320 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or (ii) for mesodermal/endodermal progenitor cells, culturing the dissociated cells from a) in suspension, in a microwell device or as an adhered culture in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 320-340 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; and (c) dissociating the cells of b) and plating the cells onto coated culture dishes comprising factors which promote cell attachment and culturing for at least 1 day in the culture media to produce ectodermal or mesodermal/endodermal progenitor cells. (a) dissociating mammalian pluripotent stem cells into clusters or single cells; (b) (i) for ectodermal progenitor cells, culturing the dissociated cells from a) in suspension and/or in a microwell device in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 260 to 280 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or adhering the dissociated cells from a) and culturing in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 270-320 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or (ii) for mesodermal/endodermal progenitor cells, culturing the dissociated cells from a) in suspension, in a microwell device or as an adhered culture in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 320-340 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; and (i) for ectodermal progenitor cells, culturing the dissociated cells from a) in suspension and/or in a microwell device in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 260 to 280 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or adhering the dissociated cells from a) and culturing in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 270-320 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; or (ii) for mesodermal/endodermal progenitor cells, culturing the dissociated cells from a) in suspension, in a microwell device or as an adhered culture in culture media for differentiating stem cells which is free of pluripotent factors with an osmolality of 320-340 mOsm/kg, wherein the osmolality is adjusted by adding sodium chloride; and (c) dissociating the cells of b) and plating the cells onto coated culture dishes comprising factors which promote cell attachment and culturing for at least 1 day in the culture media to produce ectodermal or mesodermal/endodermal progenitor cells.