Do undocumented immigrants matter as constituents for state legislators? In this study we examine legislator responsiveness to differing ethnicities and immigration statuses of immigrant constituents through a field experiment conducted in 2014 in 44 U.S. state legislatures. We advance a theory of citizen advantage, that citizens and particularly white citizens will reap greater representation from legislators, but that even undocumented immigrants can constitute a meaningful subconstituency that receives some, albeit less, responsiveness from legislators. Each legislator received a constituent request that was identical in content and varied the constituent’s race/ethnic identity by using a first name and surname cue (Latinx or Eastern European) and immigration status (undocumented/citizen/control). We found that legislators respond less to undocumented constituents regardless of their ethnicity and are more responsive to both the Latinx and Eastern European-origin citizen treatments, with Republicans being more biased in their responsiveness to undocumented residents. Nuances within the data reveal that despite limited electoral incentive, some legislators are responsive to undocumented immigrants regardless of race or ethnicity; however, when immigration status is not cued, white residents receive greater responsiveness than Latinx.