Abstract: Methods of forming multilayer reflective polarizers are described. One method includes providing a multilayer polymer film having a plurality of alternating polymeric optical layer pairs, heating the multilayer polymer film to a temperature of about or greater than both polymers layer glass transition temperatures to from a heated multilayer film, and stretching the heated multilayer polymer film in an in-plane direction to form a multilayer reflective polarizer. Each first polymer layer includes a first polyester material and each second polymer layer includes a second polyester material that has a different polymer composition than the first polymer layer composition. The stretching includes a uniaxial stretch.