This paper reports the psychometric development of new measure of paranormal and related beliefs. Based on a constructive review of the limitations of current self-report questionnaires several criteria were formulated for development of the new measure. One of the key criteria was that items had to meet an explicit definition of scientifically unaccepted beliefs, thereby allowing inclusion in the new measure of a broad range of paranormal beliefs, traditional religious beliefs, urban myths, and similar beliefs currently not accepted by the scientific mainstream. An initial pool of 92 items was administered to 1,180 Australian adults to rate in terms of the level of endorsement. The data of 600 of these participants were analysed under Item Response Theory using the Rasch model and WINSTEPS software, yielding a 20-item questionnaire with two dimensions, New Age Beliefs and Traditional Religious Beliefs, that were free from differential item functioning for age and gender and which featured interval-level measurement. Data from the remaining 580 participants were used for the purpose of confirmatory factor analysis; this analysis confirmed the previously identified psychometric structure. A second study using 236 Australian adults demonstrated the new measure possessed generally satisfactory psychometric characteristics, although further investigation of the scale's discriminant validity and of the convergent validity of the Traditional Religious Beliefs subscale is warranted. The new 'Survey of Scientifically Unaccepted Beliefs' is commended to researchers for its distinctive conceptual perspective, its elegant psychometric structure, and its sophisticated psychometric properties.