Many Latinas/os in the United States participated in the protests and rallies (i.e., collective action) to support immigrants' rights that followed Donald Trump's inauguration as U.S. President in 2017. Following the rejection-identification and rejection-disidentification models, we examined whether perceived personal discrimination, panethnic (i.e., Hispanic or Latina/o) identification, and national (i.e., American) identification were associated with greater likelihood of having engaged in collective action to support immigrants' rights among a national sample of Latinas/os in the United States (N = 1,501). We found support for the rejection-disidentification model. Perceived personal discrimination was associated with lower national identification. Latinas/os who reported lower national identification, in turn, were more likely to have reported participating in collective action to support immigrants' rights. We found less support for the rejection-identification model. Perceived personal discrimination was not associated with higher (pan)ethnic identification, although (pan)ethnic identification was positively associated with collective action. We consider the implications of these results for the rejection-identification and rejection-disidentification models and emphasize the importance of attending to U.S. Latinas/os' multiple identities.