The phenomenon in psycholinguistics known as structural priming happens, during language comprehension, when a prime sentence facilitates the processing speed of a target sentence, when both bear the same syntactic structure. In the present study, two specific passive constructions were investigated, the agentive "by"-phrase and the temporal by-phrase, to evaluate whether these structures primes each other or whether they prime themselves. On-line sentence processing measured by eye-tracking data in the form of duration of fixations within the AOIs (areas of interest) as well as fixation regressions to those AOIs corresponding to the prepositional "by"-phrases, the NP (det N), and the VP (aux V) respectively. The study yielded significant findings for priming of agentive targets with agentive primes and a failure to find priming in all other combinations of agentive and temporal prime and target conditions. The implications of these findings for an understanding of the mental representation of syntax of these constructions are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]