Bangladesh is a sub-tropical developing country, bordered to the west, north and east by India, to the south-east by Myanmar, and to the south by the Bay of Bengal with a 480km long coastline. It has made considerable economic strides in the past two decades. It is on track to achieve the Millennium Development Goals of halving extreme poverty by 2015. Poverty among the population has declined from 57 percent in 1990 to 31.5 percent in 2010 (World Bank, 2013b). Average GDP growth over the last nine years was more than 6 percent (World Bank, 2013b). The population growth rate has also slowed down markedly from 2.9 percent in 1974 to 1.34 percent in 2011 (BBS, 2011a). Nonetheless, Bangladesh is regarded as one of the most climate-vulnerable countries in the world (IPCC, 2007a; Yu et al., 2010b; Maplecroft, 2011; Met Office, 2011; World Bank, 2013a). Its vulnerability is due not only to its physiographic and climatic conditions but also to its socioeconomic conditions, poor infrastructure and high livelihood dependence on natural resources. According to the Met Office (2011), Bangladesh has experienced widespread warming (0.24°C per decade during the hot season of March to May and 0.19°C per decade during the cool season of December to February) and a small increase in total precipitation since 1960. This study also observed several temperature and precipitation extreme events in the last 5 decades. Although this study observed a long-term trend of temperature extremes, no evidence of a long term trend of precipitation extremes (i.e., continuous wet or dry days) was observed. Between the years 1985-2009 an increased rate of sea surface temperature (0.0086°C to 0.0191°C annually) was found in the Bay of Bengal (Chowdhury et al., 2012). Other studies (Mirza and Dixit, 1997; Khan et al., 2000; Mirza, 2002 ) found an increase in temperature of about 1°C in May and 0.5°C in November (from 1985 to 1998), and decadal rain anomalies above long term averages since the 1960s in Bangladesh. Shahid (2010) observed an increase in annual and premonsoon rainfall as 5.53 and 2.47 mm/year, respectively, over the period 1958-2007. Bangladeshis have a long tradition of fishing and fish culture which contribute significantly to employment, income generation, export earnings and human nutrition. This sector supports livelihoods of about 7 million fishers directly and 12 million people indirectly and contributes 4.43% to GDP and 2.73% to export earnings (DoF, 2012). Most (93%) of the marine fishing is small-scale in nature and supports the livelihoods of over half a million fishers and their household members (DoF, 2012) living in 870 fishing communities (Aghazadeh, 1994). Although no recent data is available, the number of coastal fishing communities is frequently claimed as more than 2000 in the media. In addition, marine fisheries support the livelihoods of other households involved in ancillary activities such as fish processing, gear making and so on. This study follows a mixed-method approach of data collection. Quantitative methods (e.g., structured household questionnaires) were used mainly for collecting data on context, whereas qualitative methods (e.g., oral history interviews, vulnerability matrices, key informants interviews and FGDs) were used to get rich, detailed and contextually grounded data (Nightingale, 2003). Quantitative data were analysed in two stages – after finishing the collection of structured household questionnaires data and after finishing all data collection. During the first stage, cluster analysis of the households was conducted and during the second stage composite vulnerability indices, normalization, Spearman’s rank correlation, ttest, z-test, ANOVA and descriptive statistics were carried out. Cluster analysis is described here in detail but other methods are detailed in the later chapters. This chapter has described the research design and methodology. It highlights methodological approaches including suitability of the case-study approach for this research. It also describes the study context and justifies the site selection process. Methods used for data collection have been described, including reflection upon their strengths and limitations. Issues such as the positionality of the researcher and ethical considerations have also been considered. The various techniques of quantitative data analysis have been mentioned and cluster analysis has been described in detail. The qualitative data analysis technique has also been described in detail. Throughout this chapter reliability and validity, or trustworthiness, rigor and quality of this research have been considered.