Segregation refers to the uneven spatial distribution of social groups over space. Segregation can be perceived as the spatial representation of social, cultural, and economic exclusion. There is no accepted standard way segregation is measured; instead, studies have used a wide range of methods, measurements, and indices to estimate levels of segregation. Existing studies are seldomly longitudinal in character, mostly because of lack of data, and have only been conducted until 2010 for Stockholm. The aim of this thesis is to investigate trends of residential poverty segregation in Stockholm County for the period 1991-2016. This study has utilized the isolation index, the dissimilarity index, percentile plots and location quotients on data aggregated to both administrative units and individualized neighborhoods on multiple scales to assess how these common techniques influence results. Results show that segregation patterns vary depending on technique, but most results indicate increasing levels of segregation of individuals at risk of poverty for the period 1991-2011, in line with previous research. On the other hand, the results indicate stagnating or decreasing levels of poverty segregation in recent years. Poverty segregation varies substantially by scale level, and therefore this thesis recommends multiscalar methods in segregation studies.