The sintering and mechanical characteristics of strontium-doped lanthanum manganites are increasingly important for both processing and device integration. A-site deficiency and reduced strontium fraction were shown to improve sinterability, High-strontium compositions displayed unusual mechanical properties, including unexpectedly low Young's modulus and fracture strength. In addition, plastic deformation of a fully dense LSM plate under modest loading was observed. This surprising and novel result may result from oxygen exchange with the LSM surface at elevated temperatures.