The apparel sector in the United Kingdom (UK) has seen sales growth in both the upper and lower price levels of fashion, and a contraction in the middle market. However, experts predict that, with concern about externalities created by production and consumption growing, consumers will increasingly look for more than a value proposition to determine their apparel purchases. Corporate Social Responsibility (CSR) policies published by fashion brands have traditionally concentrated on employment practices. However, with pollution created by global sourcing strategies being highlighted, including the effects of fibre production, material and garment manufacture, packaging, transportation and the disposal of used garments, brands are increasingly reflecting environmental concerns in their CSR policy documents. Applying the tricomponent attitude model, this research investigates whether social efficiency measures and externalities identified by CSR documents affect purchase behaviour in the apparel sector. Utilising a quantitative methodology, undertaken with a sample aged 18-26, the research found that CSR issues are not currently a motivating factor for this segment, where short-term individual needs of style, fit and price take precedence over long-term sustainability considerations. This paper explores apparel retailers' use of CSR documents, which contain social efficiency measures designed to address externalities created by production and consumption, and their influence on consumption in the UK apparel sector.