Practitioners often screen depression among the general population with the Center for Epidemiologic Studies Depression (CES-D) scale (Radloff, 1977). However, few studies tested the scale for bias (by gender and age) across a wide age range. This study does so with a partial credit Rasch model via Winsteps® (Linacre, 2018) on 34,762 Chinese people, 10–99 years old. Results showed one gender Differential Item Functioning (DIF) item (cry) and six age DIF items. As low positive-affect was not a good indicator of depression, its four items were excluded, yielding a 16-item CES-D (CES-D16). At the same level of depression, females report crying more often than males do. Compared to young people at the same depression level, older people felt less fearful, cried less, were bothered less often, had more sleep problems, needed more effort to do things, and could not get going more often. When using the CES-D16 to examine the general population of Chinese people across different genders and ages, researchers should pay special attention to these DIF items.