This study explores age-related differences in conformity to masculine norms between two distinct groups—emerging adults (26 and younger) and older adults (over 26)—using the Conformity to Masculine Norms Inventory (CMNI-29). The total sample consisted of 837 male participants (100%), aged between 18 and 64 years. Group distributions were as follows: emerging adults (≤ 26 years; n = 439, M = 22.42, SD = 2.16) and older adults (> 26 years; n = 398, M = 39.54, SD = 10.33). The research examined the factorial structure of the CMNI-29 in a Spanish sample, accumulated evidence of its internal validity, and tested its measurement invariance across both age groups. A novel methodological approach was applied, combining Exploratory Graph Analysis (EGA), Confirmatory Factor Analysis (CFA), and Multiple Indicators, Multiple Causes (MIMIC) models to assess changes in measurement due to the transition to adulthood. The theoretical structure was confirmed by EGA and CFA, showing scalar invariance across groups. Furthermore, significant differences in latent means were observed, with the older group reporting lower adherence to norms, particularly in winning, risk-taking, violence, self-reliance, and heterosexual self-presentation. These findings suggest that masculinity ideologies differ between emerging and older adulthood, reflecting shifts in life priorities and social expectations.