Last Friday Gov. Gerald L. Baliles opened the doors of the Executive Mansion and threw a birthday party for his wife Jeannie unlike any seen in the four years of his predecessor, Charles S. Robb.

Gone were the police checks of anyone entering the mansion and the polite but formal parties that the Robbs threw. Baliles opened the house to a wider community, including the media.

The music for Jeannie Baliles' 43rd birthday came from a rock band, Baby Huey and the Babysitters. And the revelers, some of them wearing "boldly cautious" buttons that mocked one of Baliles' sayings, danced until midnight. The governor himself was there downing an beer or two as he worked the crowd.

It was symbolic of the tone Baliles has attempted to set for his administration, a style that helped win the 46-year-old Democrat high marks for his handling of the recent 60-day session of the legislature.

Baliles' report card, however, will be incomplete until September because he delayed his biggest legislative test until then. That's when the state's 140 legislators return to Richmond for a special session to wrestle with how to fund the state's massive transportation needs.

Baliles, who is traveling around the state this week "building public support and outlining the scope" of the roads issue, said separating transportation from the other questions was "part of my strategy for getting roads built."

Speaking at the dedication of an industrial park in Danville on Monday -- remarks he is likely to repeat at the Wednesday night before the Arlington Committee of 100 at Marymount College -- Baliles called the regular 1986 legislative session "a great success."

He said legislators went home last weekend "knowing they had crafted a milestone in the history of our state's economic development." But he warned that "unless we vastly improve Virginia's transportation system, our economic development efforts will be for naught."

Praise for the new governor's first legislative session was strong and came from both Democrats and Republicans. Lt. Gov. L. Douglas Wilder, elected in November with Baliles in a second consecutive Democratic sweep of the top Virginia offices, said "Jerry exhibited a hands-on knowledge" of the legislature during the session. Citing Baliles' service in the General Assembly and his four years as attorney general, "There was no incubation period needed," Wilder said.

"Baliles had a good first session," said Del. Robert E. Harris (R-Fairfax). "In your first year, you just want to make sure you don't shoot yourself in the foot -- and he didn't."

There were inevitable comparisons with Robb and many of them were favorable to Baliles.

"Robb regarded this place as a nest of tarantulas when he first came," said Sen. Joseph V. Gartlan Jr. (D-Fairfax). "He [Baliles] involved himself more . . . . He was much more willing to put himself on the line and not delegate as much."

"Robb's first year was pretty rocky," said Del. Ford C. Quillen (D-Scott). "Baliles' first year was much smoother than Robb's first year . . . . His knowledge of the legislature really paid off."

Baliles said he "enjoyed the intellectual challenge" of "working with those who had problems with his agenda and those who were entirely supportive."

A key legislator who fit into the former category, Senate Finance Committee Chairman Edward E. Willey (D-Richmond), said Baliles "got along very well, but he didn't have any big programs."

Willey, long regarded as the most powerful member of the legislature, was among those who caved in to Baliles, agreeing to give up on his own gasoline tax increase in favor of a lesser measure backed by the governor.

Early in the session, Baliles named Willey chairman of the Commission on Transportation in the 21st Century, which is charged with recommending to the special session ways of funding massive transportation projects.

At the start of his administration, Baliles said, "I like to keep score," and on Saturday, he announced that the legislators had passed all but three of the 118 bills that his administration had specifically requested.

Under the Baliles counting method, bills that passed despite the opposition of the administration were not counted nor were bills that his administration supported but did not request be introduced. Baliles, for example, supported a mandatory seat belt bill, but it was introduced by a legislator without the governor's request.

The only measures Baliles said he had requested that did not pass would have allowed the state police to check speed of vehicles from airplanes, ordered parents or guardians who were capable to pay a portion of the cost of juvenile placements, and accelerated motor fuel tax payments.

Baliles said he was especially proud that he was able to win approval for dividing the cabinet position of secretary of commerce and resources into separate secretaries for economic development and natural resources, which had failed in the previous administration.

It wasn't all a love feast.

Del. Vincent F. Callahan Jr. (R-Fairfax) said, "He was generally invisible. The only time he surfaced was on the gas tax."

Callahan said, however, that Baliles "will pay more attention to Virginia than Robb did, he won't be a national governor. I don't think he'll be as cautious."