Tensile stress strain curves were obtained for single crystals of lithium fluoride. The specimens were elongated at room temperature along a ⟨100⟩ axis. The number of slip‐band sources was controlled by surface treatment. Both the yield stress and the flow stress in the plastic range were found to depend on the number of active slip bands. The shapes of the stress‐strain curves were related to the behavior of individual dislocations in lithium fluoride.