The kings of Norway issued coins on a regular basis starting in the mid-11th century, and probably conducted renovatio monetae whenever a new king came to power. As a privilege of bona regalia, the king could use coin production to serve his own interests. Economic factors are usually the main focus of discussions on coinage, but there were also political, religious and cultural dimensions that must have been important both for the production of coins and in the choice of motives, form and style. From the outset, manipulation of the coinage is visible in the debasement of silver content, followed by a reduction in weight to re-establish the silver level.  In the 12th century, the weights continued to drop and single-faced coins and bracteates became the standard; only a few biface coins are known. These small coins and bracteates from the 12th century carry little or no information concerning issuer, date or place of production. This lack of information has resulted in a gap in our knowledge about the role of these coins in medieval society in Norway. This role was dependent both on the intentions of the producer and on how the coins were perceived by the people, and their will to use them in certain ways. What were the reasons behind issuing the smallest coins ever produced in coin history, and what impact did this dramatic reduction in weight have on the understanding and use of the coin? To advance the discussion it has been vital to establish new knowledge about chronology, coin-issuing authority and mints. These areas have been addressed through two analyses using numismatic and archaeological methods. The results of the initial analyses are combined with an investigation of the size of the coin production and a study of archaeological contexts, in order to reveal how, where and when the bracteates were used.  The theoretical approach to understanding the role of coins is inspired by theories in anthropology and sociology about the many ways in which money can be incorporated in a society, emphasising the complex social component of coins in contrast to the traditional economic emphasis on their neutral qualities as a means of exchange. Central to this are the concepts behind formalism and substantivist and post-substantivist theory. The study concludes with a discussion that explores what can be said about economy and economic systems based on the 12th-century Norwegian coins.