Recently there has been a robust discussion on the question of Latina/o racial subjectivity, particularly whether Latinas/os are more apt to identify as "white" or as people of color. Scholars focused on contemporary identification patterns have examined key variables, including age, education, income, and nativity in an effort to understand Latinas/os' racial choices. However, dimensions of time and space are frequently unanalyzed. Focusing on the seven-county region of Southern California—home to the United States' largest concentration of Latinas/os—we use the American Community Survey (2008-10) to consider a range of variables, including spatial and temporal characteristics, to better understand Latina/o, especially Mexican American, racial subjectivity. Focusing on Latinas/os who identify as either "white" or "some other race" and utilizing a regression analysis to isolate the relative impact of each variable, we find that Latinas/os who live in more segregated neighborhoods as well as those who live among a high proportion of Latinas/os, are more likely to identify as "some other race."