This dissertation investigates the Old English word field for the concepts of ‘pledges’ and agreements by analysing the words belonging to the field in their contextual environments. The particular focus is on the word wedd (‘pledge’), which is shown to have different connotations in different text types. The main subject of the study is the corpus of Anglo-Saxon legal texts in which pledges played an important part. Pledges occur in collocation with concepts such as oaths (að) and sureties (borg), but there are important differences in function and linguistic usage between the terms. One important aspect of the language of pledging is the formulaic word pair að and wedd which comes to stand for the entirety of legal interactions, as no single word for ‘legal agreement’ is used by authors of legal prose. Possibly in part influenced by this development, the meaning of wedd, which originally denoted an object given as a pledge, becomes more abstract. The study further argues that this development is facilitated by the influence of Christianity. Old English words were required to express unfamiliar aspects of the new religion. I analyse words used to translate biblical covenants in detail. Because of its specifically legal overtones, wedd was employed by Anglo-Saxon translators and commentators to take on the functions of Latin words with a wider range of meaning, such as foedus or pactum. In its narrower sense wedd is important in the theology of sacraments. I show that the Eucharist and baptism are modelled on types of pledges from the legal social world that would have been familiar to Anglo-Saxon homilists and their audience. That this is a conscious decision on the part of Anglo-Saxon authors is indicated by the fact that this aspect is often added to their adaptations of orthodox Latin sources. An analysis of pledging in Old English poetry shows that wedd was rarely used by Anglo-Saxon poets, even in the adaptation of biblical texts which were shown to employ wedd as a deliberate lexical choice in their prose versions. In poetry, the equivalent term is wær (‘agreement’ or ‘treaty’). I argue that this difference can be explained by the fact that wedd was a technical term, belonging to the register of legal language, where wær never occurs. It is argued that wedd, possibly because of its legal connotations, was not a common word for Old English poets and is only used occasionally, mostly for purposes of poetic variation. I suggest that this is connected to the early date of some of the poems and to the traditional and possibly slightly archaic nature of Old English poetic language