The Office for National Statistics has published a bulletin presenting annual statistics on family and household structure in the UK. A family is a married, civil partnered or cohabiting couple with or without children, or a lone parent with at least one child. Children may be dependent or non-dependent. Types of family include married couple families, cohabiting couple families and lone parent families.

Key findings of the bulletin include:

• In 2011 there were 17.9 million families in the UK. Of these 12.0 million consisted of a married couple with or without children.
• The number of opposite sex cohabiting couple families increased significantly, from 2.1 million in 2001 to 2.9 million in 2011. The number of dependent children living in opposite sex cohabiting couple families increased significantly, from 1.3 million to 1.8 million over the same period.
• In 2011, 38% of married couple families had dependent children, the same percentage as cohabiting couple families.
• There were 2.0 million lone parents with dependent children in the UK in 2011, a figure which has grown steadily but significantly from 1.7 million in 2001.
• There were 26.3 million households in the UK in 2011. Of these 29% consisted of only one person and almost 20% consisted of four or more people.