Large effective area optical fibers are disclosed. In one embodiment, an optical fiber includes a glass core and a glass cladding surrounding and in direct contact with the glass core. The glass core may include a radius Rc from about 12 μm to about 50 μm; a graded refractive index profile with an alpha value greater than or equal to about 1.0 and less than about 10 at a wavelength of 1550 nm; and a maximum relative refractive index ΔcMAX% from about 0.2% to about 0.75% relative to the glass cladding. An effective area of the core may be greater than or equal to about 150 μm2 such that the core supports the propagation and transmission of an optical signal with X modes at a wavelength of 1550 nm, wherein X is an integer greater than 1 and less than or equal to 110. The glass cladding may include a maximum relative refractive index Δc1MAX% such that ΔcMAX%>Δc1MAX%. The optical fiber has an RMS pulse broadening of less than or equal to about 0.15 ns/km at a wavelength of 1550 nm.