This thesis investigates the system of compounding attested in the earliest written Latvian texts of the 16th and 17th centuries. The philological analysis presented in this work is the first systematic attempt to extensively treat compounds in Old Latvian. The purpose of this thesis is to thoroughly describe the system of compounding of the earliest period of written Latvian. One of the main aims of the analysis provided in this work is to determine whether the Old Latvian compounds were distinguished in terms of their meaning and form. This is why another important aim of this study is to discern the most characteristic formal properties of each category of compounds in Old Latvian. This study also addresses the morphological variation of the components of compounds and seeks to explain why one finds different tendencies of compounding in the texts of this period.    Firstly, it is shown in this thesis that compounds in Old Latvian were clearly distinguished in terms of their meaning. The main semantic types of Old Latvian compounds, which were analyzed in this study, are the determinative compounds, the possessive compounds, the verbal governing compounds, and the copulative compounds. Secondly, it is argued that the aforementioned types of compounds were clearly differentiated in terms of the formal properties of their components. A large number of possessive compounds and verbal governing compounds had the compositional suffix -is (m.)/-e (f.). By contrast, only a handful of determinative compounds had this suffix. In view of the distribution of the suffix found in the Old Latvian compounds, it is suggested that the suffix was originally restricted to adjectival compounds. Furthermore, the different types of compounds in Old Latvian were also distinguished in terms of the first component. In the majority of cases, both the possessive compounds and the verbal governing compounds were coined without linking elements, while the determinative compounds had linking elements to a larger extent. Thirdly, it is proposed in this thesis that a part of linking elements used in the determinative compounds in Old Latvian originated from the original stem vowels of the first components. Thus, it is argued that stem compounds were still attested in the Old Latvian texts, although this Baltic model of coining compounds is no longer visible in Modern Latvian. Lastly, it is suggested that the tendencies of compounding found in the texts under discussion represent dialectal differences. Another contribution of this study is that the Old Latvian compounds are not treated in isolation, but analyzed in drawing parallels with compounds in the other Baltic languages, Lithuanian in particular. Hence, by analyzing common features and similarities between the compounding systems, the Old Latvian compounds are positioned within the context of the Baltic system of compounding.