This test method covers the determination of the low-rate fracture toughness (JIc) of polymeric materials exhibiting a ductile behaviour, characterized by macroscopically stable crack growth during a fracture test. The application of standard linear elastic fracture mechanics (LEFM) tests to these materials typically fails due to the excessive non-linearity in the response. This test method, developed for the SE(B) testing configuration, describes a single-specimen approach that does not require the measurement of the crack extension, Δa.