Frédéric de Liancourt was elected to the Estates-General of 1789, where he sought in vain to support the monarchy while furthering social reform.

On 14 July, following the storming of the Bastille, he warned Louis XVI of the state of affairs in Paris, and met his exclamation that there was a revolt with the answer, "Non, sire, c'est une révolution."

Established in command of a military division in Normandy, he offered Louis a refuge in Rouen, and, failing in this effort, assisted him with a large sum of money.

At the Restoration he entered the House of Peers, but Louis XVIII refused to reinstate him as master of the wardrobe, although his father had paid 400,000 francs for the honour.

[5] Rochefoucauld was one of the first promoters of vaccination in France; he established a dispensary in Paris, and he was an active member of the central boards of administration for hospitals, prisons and agriculture.

His opposition to the government in the House of Peers led to his removal in 1823 from the honorary positions he held, while the vaccination committee, of which he was president, was suppressed.

His eldest son, François, duc de La Rochefoucauld (1765–1848), succeeded his father in the House of Peers.

The third son, Frederic Gaetan, marquis de La Rochefoucauld-Liancourt (1779–1863), was a zealous philanthropist and a partisan of constitutional monarchy.

The marquis wrote on social questions, notably on prison administration; he edited the works of La Rochefoucauld, and the memoirs of Condorcet; and he was the author of some vaudevilles, tragedies and poems.