The presence, status and earnings of women in paid employment has improved dramatically in Australia over the past half century, with positive efforts to achieve equality through legislation such as the Sex Discrimination Act 1986 and decisions in the Industrial Relations Commission within what was, until the late 1980s, a centralised wage fixing system. During the past two decades, however, there has been no sustained narrowing of the gender pay gap using the broadest measure - average weekly ordinary time earnings (AWOTE) for full-time wage and salary earners. Moreover, there is recent evidence that the gender pay gap has started to widen again. By 1992, the gender pay gap in Australia had narrowed to approximately 16 per cent, and then fluctuated around that figure for over a decade. However, recent data from the Australian Bureau of Statistics' (ABS) Average Weekly Earnings Survey has indicated that it is now back at a 21 year high of 18 per cent as of February 2010 (ABS 2010). Narrower measures of gender pay inequality also suggest that the gender earnings gap is not restricted to general workers, and is sustained at senior executive level (EOWA 2009) and even amongst new university graduates (GradStats 2009). This chapter explores some of the data around the gap in AWOTE between male and female earnings as well as other measures of gender pay inequality. It also explores some of the reasons that have been put forward to explain the existence of the gaps and the patterns of gender pay inequality.