The process of development and testing of the Lang and Goulet Hardiness Scale (LGHS), a self-report instrument designed to measure hardiness in bereaved parents following the death of their fetus/infant, is presented. Hardiness is a personal resource, composed of 3 interdependent components that are characterized by a sense of personal control over the outcome of life events and hardships such as the death of a fetus/infant, an active orientation toward meeting the challenges brought on by the loss, and a belief in the ability to make sense of one's own existence following such a tragedy. The concept of hardiness has been studied by various disciplines and in a multitude of settings to understand its ability to lessen potentially negative effects of life stress. However, it has never been studied within the context of parental bereavement. The LGHS was developed systematically, originating from a concept analysis. A panel of 15 experts was used to establish content validity.A pretest was conducted on 73 bereaved individuals to assess convergent and discriminant validity of the LGHS. Subsequently, a validation study on 220 bereaved parents who had experienced the death of their fetus/infant 2 months previously was conducted including a retest 6 months after the loss with 192 of the remaining participants. Analyses reveal that the LGHS is a valid and reliable instrument for measuring hardiness and that it is sensitive enough to detect changes in the construct over time.