This dissertation explores case and verbal agreement in Icelandic. Case and agreement generally pattern together, but there are exceptional instances in which case and agreement come apart. In Icelandic, verbs agree with Nominative DPs. However, in some constructions, agreement with a Nominative is optional. In the standard account of case and agreement (Chomsky 2000), both types of features are determined simultaneously via the same syntactic operation. The standard theory, therefore, predicts that case and agreement should pattern the same way, and that neither should be optional. Moreover, based on fieldwork conducted at the University of Iceland, I present data that has not heretofore been reported. I argue that the likelihood of agreement depends on the type of construction. My research builds on other work which addresses optionality in Icelandic agreement (e.g. Sigurðsson and Holmberg 2008). This dissertation makes a substantial contribution to the literature on Icelandic agreement in that the rate of agreement across various types of constructions has not been examined. I illustrate that this type of optionality is not only robust, but also systematic. This dissertation contributes to the larger literature on case and agreement in several important ways. First, I argue for a departure from the standard proposal that case and agreement are established via the same syntactic operation. I propose that it is possible for the probe which assigns case to be in a relationship with a DP, even though the probe which establishes agreement is not in a relationship with that DP. Second, I provide empirical support for Multiple Agree. I argue that the survey findings reported in this dissertation provide evidence that a probe can enter into a relationship with more than one goal. Third, I provide empirical evidence for the optionality of Multiple Agree. I argue that agreement is optional only in constructions in which there is an item intervening between T and the Nominative, and Multiple Agree is, thereby, required in order for an agreement relationship to be established.

This work catalogues the verbal agreement paradigm of Kanyen'keha in greater detail than has previously been done. The cataloguing includes the complete intransitive, transitive, and reflexive paradigms, and description of all argumental contrasts to which the verbal agreement is sensitive. It also describes in detail the contexts where feature sensitivity is blunted, and the patterns of syncretism in the verbal agreement. Based off of this descriptive work, this work evaluates the accuracy with which previous analyses treat verbal agreement in Kanyen'keha. Finding room for improvement in these analyses, this work proposes a new analysis of Kanyen'keha, which claims all verbal agreement in transitive contexts to be realized from one agreement probe, which enters into Multiple Agree with subjects and objects. This style of analysis allows for many aspects of the agreement to be accounted for, including person hierarchy effects, distribution of portmanteau morphology, and complex dependency between the multiple morphemes which comprise the agreement / Thesis / Master of Science (MSc) / This thesis describes the verbal agreement of Kayen'keha in greater detail than has previously been done. This thesis also evaluates the claims of previous work done on verbal agreement of Kanyen'keha, describing where such work accurately accounts for the agreement and where it does not. Finally, this thesis proposes a novel analysis of Kanyen'keha verbal agreement.