President Reagan enhanced his position as a leader of the Western powers at the seven nation economic summit held here over the Memorial Day weekend. As a result, he also may have boosted his political standing at home.
Mr. Reagan's aides note that his position in public opinion polls is growing stronger, thanks in large part to economic recovery in the United States. This trend, plus the added lift from his role here, should keep him in a strong position into the summer, when he is expected to decide whether to seek a second term.
The summit outcome also is likely to strengthen Reagan's hand with Congress. A rebuff of Reagan by America's economic and defense partners could have emboldened Congress as it continues to debate the budget and United States arms policy.
Instead, in colonial Williamsburg's setting of fine old brick-and-board buildings - a splendidly restored reminder of America's cross-Atlantic origins and maturity as a democracy - Reagan won endorsement of a common arms negotiation stance toward the Soviet Union, largely along policy lines the US favors. For the first time, France and Japan were included as cosigners of such a statement.
And, steering through a rocky course of criticism of US deficits and interest rates, he won endorsement of his conservative economic agenda, which calls for noninflationary growth in the West and a slow, ''sustainable'' recovery from world recession. He conceded little in policy terms to bids for monetary system reforms, or to widely held fears that the fledgling US-led recovery will do little for European unemployment.
But the Reagan arms and economic initiatives succeeded at a price.
Much as Reagan had to assure moderates in the US Congress last week he would use their approval of MX missile development mainly to bargain for arms reducations with the Soviets - a logic that nonetheless troubled many Reagan critics in Congress - Reagan again had to stress negotiation with the Soviets in the Williamsburg statement. This helped balance more hawkish phrases, like a warning to the Soviet Union that ''we shall maintain sufficient military strength to deter any attack, to counter any threat, and to ensure the peace.''
The result was a patchwork of postures that mingled the stern with the olive branch.