As will be discussed in this chapter, monitoring the SDGs from a gender equality perspective is constrained by three main challenges: first, uneven coverage of gender-specific indicators, with some goals lacking indicators to capture gender equality outcomes, second, gaps in gender data, including data on women and girls experiencing multiple and intersecting inequalities (see Chapter 4), and third, quality and comparability of available data across countries and time. Gender statistics are critical to monitor the gender impact of economic, social and environmental policies. Over the past 40 years, there have been vast improvements in the generation and use of gender statistics, including international standards and protocols for the collection of violence against women data as well as time-use data (see Chapters 5 and 6). Yet, despite these advances and the growing acknowledgement of the importance of gender statistics for designing policies and assessing progress towards gender equality, gaps remain and are extensive.