Perceptions of mentors' practices related to primary science teaching from nine Australian universities (N = 331 final-year preservice teachers) were gathered through a literature-based instrument. Five factors that characterize effective mentoring practices in primary science teaching were supported by confirmatory factory analysis. These factors, namely, personal attributes, system requirements, pedagogical knowledge, modeling, and feedback, had Cronbach alpha coefficients of internal consistency reliability of 0.93, 0.76, 0.94, 0.95, and 0.92, respectively. Final model fit indexes were [chi][squared] = 1335, df = 513, CMIDF = 2.60, IFI = 0.922, CFI = 0.921, RMR = 0.066, RMSEA = 0.070 (p less than 0.001). Specific mentoring interventions for improving primary science teaching practices may be implemented by measuring preservice teachers' perceptions of their mentoring with a valid and reliable instrument.