Religion; sociology; politics; migration; economic history; crime and punishment; education; commerce; transport; folk customs, lore and tales; children's lore; proverbs; sociolinguistics and dialectology; technology; medicine; farming and rural life; cooking and house-keeping; crafts; manufacturing and manufactured goods; buildings; vernacular architecture; folk music, song and dance; the eisteddfod; pastimes; geography; topography; biography and memoirs; genealogy; personal and place-names; heraldry; Welsh history; musical instruments; handicrafts; clocks; arms; furniture; textiles; costume and accessories.

The scope of the Museum, strictly, is the history of these subjects in Wales in the post-medieval period, but they cannot be interpreted properly without considering the British, European, and up to a point, world-wide contexts, and this is reflected in the Library's collection. It contains approximately 40,000 volumes, 200 maps, and 260 current periodical titles.