Background: The development of instruments to measure aging attitudes is an essential part of research into the role of individual differences in the aging process, giving clarification to the relationship between attitudes and behavior across the lifespan. Here we test the structural validity of Lasher and Faulkender's (1993) Anxiety about Aging Scale (AAS), and explore measurement invariance across age and gender. Methods: A sample of 783 adults (42% females) age ranging from 20 to 97 years (M = 57.3, SD = 13.66) participated. Results: The first-order four-factor AAS model reflecting the original Lasher and Faulkender (1993) structure showed a better fit to the data than the second-order model. Measurement invariance for both gender and age groups (young adults 20-44 years; mid-aged adults 45-64 years, older adults 65+ years old) was found for three of the factors, but not for all items in the Fear of Losses factor. Structural covariance inequality between the Fear of Losses and Physical Appearance factors was shown between males and females. Conclusions: Findings indicate that the original AAS measures four distinct dimensions of anxiety about aging. These dimensions were shown to be generally comparable across age and gender, indicating that the AAS is a suitable measure for providing meaningful comparison of anxiety about aging across the lifespan. The exception is the Fear of Losses factor, where items may have differential meanings across groups based on cultural and social attitudes regarding aging and gender.