The aim of this master thesis is to measure library service quality in two groups of libraries, newly developed and well established, and to see if there are any differences in the users perception of the dimensions in LibQUAL+. The thesis also examines the different perception of quality for the user groups: undergraduate students, graduate students, and faculty. Another approach is to test the Swedish translation of LibQUAL+. Different theories on service quality are presented but the main theories are from the marketing perspective. The grounding and development of LibQUAL+ is described as well as the use of the instrument in different libraries. The use of quality measures in libraries is also discussed. The results from the LibQUAL+ survey show that there are no differences between the two groups of libraries. There are however differences in the perception of quality among user groups. Faculty and graduate students perceive a higher quality in the dimensions Affect of service and Library as place than undergraduate students. Undergraduate students rate the Library as place higher than the other groups. The most important dimension for all users is Control of information. This dimension has negative Adequacy gaps for this survey. Four percent of the users experience the instrument as difficult to use. Despite this I believe that LibQUAL+ is well suited for library quality measurement and development, because of its rapid delivery of results. The instrument is also well suited for benchmarking and international comparison.