Experimental work on islands has used formal acceptability judgment studies to quantify the severity of different island violations. This current study uses this approach to probe the (in-)violability of definite islands, an understudied island, in offline and online measures. We conducted two acceptability judgment studies and find a modest island effect. However, rating distributions appear bimodal across definites and indefinites. We also conducted a self-paced reading experiment, but found no sig- nificant effects. Overall, offline, definite islands differ from other uniform islands, but online, the results are more complicated.