WASHINGTON — One accusation long directed at Congress is that lawmakers come to this capital city not just to serve the American people but also to enrich themselves and their families.

For the House of Representatives, at least, there is now an encyclopedia of sorts that reinforces this suspicion.

A nonprofit ethics group here spent the last nine months examining every member of the House — for campaign spending, budget earmarks, office accounts and lobbying by any relatives — and found that the families of more than half of all the House lawmakers have received payments or otherwise benefited financially from their affiliation with a lawmaker in the two previous election cycles.

The 346-page report by Citizens for Responsibility and Ethics in Washington, or CREW, is an extraordinary compendium of creative accounting, self-interested budgeting and generous expense reimbursements. It highlights common practices that translate into tens of millions of dollars in payments to relatives or the lawmakers themselves.