Using a cross-sectional survey research design, this study explored the latent profiles of 247 in-service and 459 pre-service teachers' perceptions of the omitted or neglected parts of teacher education programs in Türkiye regarding 21st-century skills, with the intention of examining whether these profiles substantially differed between the in-service and pre-service teacher samples. Both groups were asked to respond to a null curriculum questionnaire for 21st-century skills. Preliminary analyses revealed that the factor structure of the questionnaire had a good fit for both in-service and pre-service teachers' data and was invariant across samples and gender. Based on the results of the latent profile analyses, three profiles (the fully omitted/neglected 21st-century skills profile, the moderately omitted/neglected 21st-century skills profile, and the well-captured 21st-century skills profile) were identified among in-service teachers. Conversely, four profiles were identified among pre-service teachers (the highly omitted/neglected 21st-century skills profile, the fully omitted/neglected 21st-century skills profile, the moderately captured 21st-century skills profile, and the fully captured 21st-century skills profile). The results showed that, with one exception (i.e., the fully omitted/neglected 21st-century skills profiles), the characteristics of these profiles were not comparable across the two samples.