FORT WASHINGTON, PA. -- Soon after Robert E. Cawthorn became chief executive officer of Rorer Group Inc., he convened an all-day meeting of senior managers to rethink the direction of the company. At the time, May 1985, Rorer's future was precarious.

The company's prospects are brighter now, as Rorer prepares to acquire A.H. Robins Co. The merger, valued at $2.6 billion, would create a pharmaceutical powerhouse with best-selling products in five categories. Its annual sales after the merger would exceed $1.5 billion.

Two years ago, however, when "Rob" Cawthorn and his team plotted their strategy, Rorer's situation did not look nearly as promising. The company ranked as a distant also-ran in the drug business and was losing ground. Its growth in earnings lagged the industry average.

Rorer lacked the money to compete effectively in developing new products, essential to a drug company. Several industry giants were spending more on research alone than Rorer reported in annual sales.

Such handicaps made the company an obvious takeover target. Rorer had weathered a bruising proxy fight that threatened its independence, but speculators still held large blocks of its stock. Wall Street assumed the company eventually would be bought out.

Cawthorn had more ambitious ideas, however. Looking back, he said recently that he always had "a tendency to think big."

Despite its problems, Rorer possessed several strengths. Its principal product, Maalox, was the world's best-selling antacid, bringing in plenty of cash. The cash gave the company the ability to borrow money for acquisitions.

By narrowing its focus and concentrating on a couple of market niches, Rorer could probably survive and perhaps even flourish, management consultants told the company.

At the end of the planning session, Cawthorn drafted several long-term goals for Rorer. His targets went far beyond mere survival.

Rorer's mission, Cawthorn wrote, is to be "a world-class health-care products company in every respect. This means a company that can compete effectively in selected therapeutic areas with any other company in the discovery, production and marketing of products which improve the health of mankind."

Back then, he said, "most of us just thought that statement was absolutely pie in the sky ... not a practical goal."

Barely two years later, Rorer is on the verge of becoming the world-class competitor that Cawthorn envisioned.

The Robins merger, outlined in a definitive agreement approved by the Robins board earlier this month, would propel Rorer into the ranks of the country's largest drug companies.

So far the company's ascent has been based on its new-found success in the board room rather than hot discoveries from the lab. The Robins deal marks the second acquisition in as many years for Rorer, a coup in an industry with a scarcity of candidates for purchase and an abundance of potential buyers.

Chemical companies such as Du Pont, Dow, Monsanto and Eastman Kodak have been trying to expand their pharmaceutical operations through acquisition. So have consumer-products companies such as Procter & Gamble and American Home Products.

Nevertheless, Rorer is walking off with the prizes.

In November 1985, the company agreed to pay $690 million in cash for two pharmaceutical units previously owned by Revlon Inc. The deal doubled Rorer's size, pushing its annual revenues to more than $800 million. The Robins merger will double the size of Rorer again.

Surprisingly, the architect of these bold corporate moves is one of the quietest and least visible chief executives in the industry -- and perhaps the most unusual.

At 51, Cawthorn is younger than the top officers of most drug companies. Though his hair is nearly white, he wears it over his ears and almost down to his collar in a strikingly uncorporate style.

A native of Great Britain, Cawthorn retains many British mannerisms. He "read" agriculture at Cambridge, then became a farmer, realizing an ambition he had held since his childhood in a pastoral part of northern Britain. His father, who once hoped to become a veterinarian, appraised and arranged sales of country estates.

In 1960, after completing school, Cawthorn moved to northern Alberta in Canada in search of affordable farmland. He emigrated "because the opportunities in England were too limited."

"I didn't like what I saw was happening there," he said. "The whole level of service, the level of caring and the work ethic were deteriorating... . It wasn't a very appealing prospect."

Cawthorn's dreams of farming in North America soon were defeated, however, by the short Canadian growing season, his inexperience and lack of money. "I wanted to farm in a big, mechanized way," he said, "and you can't do that without an awful lot of capital, which I didn't have."

These days, Cawthorn works the land in a small way, tending a vegetable garden and a couple of fruit trees on his 10 acres in Gladwynne, Pa.

In 1961, unable to afford the farm he wanted, he went to work for Pfizer Inc., selling animal-health products. Pfizer was just beginning to build a Canadian agricultural division, and he became the unit's first sales representative.

Cawthorn's career with Pfizer provided his basic management education. "The environment was very much one of giving people a lot of rope," he said, "putting them into new positions before they were ready and letting them grow into them. ... That develops people very quickly." Within eight years, he was made president of Pfizer Canada.

In 1973, Pfizer moved him to Nairobi to build up its operations in Africa and the Middle East and then, in 1979, to Brussels to become executive vice president of its European division.

"When I got to Europe, the business was pretty well built," Cawthorn said. His job consisted of running what was already there.

"I realized that what I enjoyed doing is building things," he said, so he took an offer from a group of venture capitalists to run the business side of a new biotechnology company, Biogen N.V., based in Geneva.

That was the opposite end of the spectrum from Pfizer, he said, "the ultimate building challenge."

Though Biogen's university-based researchers produced a number of exciting breakthroughs, the company had trouble applying its high-powered technology to commercial products. Cawthorn and Biogen's chairman, Walter Gilbert, could not agree on priorities.

Gilbert, a Nobel laureate in chemistry, favored more basic research while Cawthorn pushed for product development.

In Philadelphia, Alan Dalby, an old friend from the days in Canada, knew of Cawthorn's disenchantment at Biogen. Dalby, then an executive vice president at SmithKline Beckman Corp., eventually led Cawthorn to Rorer.

At a professional meeting in Washington, Dalby accepted an invitation to fly back to Philadelphia with John Eckman, chairman of Rorer, in the company helicopter.

During the flight, Eckman confided that he was looking for someone to head Rorer's international operations. The executive in that post had been a strong candidate for the top job at Rorer until he was stricken by a degenerative nerve disorder, leaving Eckman without an obvious successor.

Dalby, who was in the running for bigger things at SmithKline, wasn't interested, but he directed Eckman to Cawthorn. Two months later, Cawthorn left Biogen and joined Rorer. Dalby later collected a hamburger as his finder's fee when Eckman and Cawthorn treated him to lunch at the Union League.

In 1984, as Eckman neared retirement, he promoted Cawthorn to president. A year later, Eckman stepped down as CEO, and Cawthorn succeeded him. Eckman retired as chairman last year, completing the transition.

A colleague of both men said that Cawthorn was not promised the top job when he moved from Biogen but that the possibility was discussed.

Since taking over, Cawthorn has transformed the once-sleepy Rorer into a faster-moving and more opportunistic organization, primarily by introducing management techniques he learned at Pfizer.

''After we established that mission statement, everything we've been doing has been to try to move us in that direction,'' Cawthorn said.

Management by objective is ''mostly a communications system,'' he said. ''Communicating to people what's expected of the organization and what is expected of them, then coming to mutual agreement on how it is we will know whether it has been done or not.''

The essential ingredient that makes it work is money. ''We're paying for results,'' he said.

Cawthorn and his team overhauled Rorer's compensation system and beefed up provisions for bonuses to create strong incentives for performance. ''We want to pay at least an average base salary,'' he said, ''then give people the opportunity to earn well-above-average total compensation based upon results.''

Under the system, Rorer's 500 managers generally can earn cash bonuses of up to 30 percent of their base salary. Half the bonus depends on the performance of their own division and Rorer as a whole. The other half is tied to personal performance. For superior work, the bonus can jump to 45 percent.

''At Biogen, I learned that the sense of urgency makes things move more quickly,'' Cawthorn said. In the rapidly developing field of biotechnology, scientists needed to exploit their breakthroughs and stake out critical patents ahead of competitors. ''A lot of large corporations have lost that sense of urgency,'' Cawthorn said.

''We can't outspend the big pharmaceutical companies,'' he said. ''We can't outmuscle them in any area. We have to be smarter and quicker.''

So far, the changes seem to be paying off. By acting swiftly and adroitly, Rorer was able to acquire the Revlon units before competitors even realized they were for sale.

In a bidding war for Revlon's units, ''we wouldn't have stood a chance,'' said Gerald B. Rorer, vice president of the company and a descendent of the founder. ''And we might not have had the stomach for it.''

When Cawthorn formulated Rorer's mission statement, he realized that the company would have to make acquisitions to reach its goal. A team of executives went to work evaluating possible candidates. Their list included the subsidiaries owned by Revlon.

That fall, financier Ronald Perelman proposed a hostile takeover of Revlon. To escape from Perelman, Revlon proposed a leveraged buy-out at a higher price.

As it became clear that Revlon was almost certain to be broken up, Rorer approached Perelman and told him it would pay about $700 million for the pharmaceutical units, based on an evaluation made earlier by the acquisition team.

With Rorer's offer in hand, Perelman raised his bid for Revlon and carried the day. After Perelman prevailed, other drug companies came up with more generous offers for the two pharmaceutical units.

''We didn't have a written contract at that point,'' Cawthorn said. ''We were both sort of going on good faith.'' Perelman stuck to the bargain, and Rorer ended up with the prize.

The subsequent handling of the Revlon units probably played an important role in persuading Robins last month to agree to a merger. Cawthorn's evenhanded approach provides an insight into the management style that has fueled the company's growth.

To integrate the Revlon operations into Rorer, Cawthorn appointed a transition team of five executives from Rorer and five from the Revlon units. Neither side held an advantage in deciding which facilities would be closed and which executives would lose their jobs in the consolidation.

''Their focus was on making the best business decision,'' Cawthorn said. ''If I were seen to be playing favorites, it wouldn't have worked at all.''

The task force decided several Revlon executives were better qualified than their Rorer counterparts. One casualty was Rorer's chief financial officer, James S. Lyons, who had arranged the financing for the Revlon deal.

Earlier this year, as it became clear that Robins would have to be sold to satisfy legal claims against the firm, a number of suitors made offers, including Dow Chemical, Pfizer and American Home Products. Members of the Robins family, who control the company, feared the business would be dismembered and sold off piecemeal.

Cawthorn had been ''very persistent over time in expressing our interest in Robins,'' said Gerald Rorer. Chief executives of larger companies probably did not devote as much time and attention to the deal, he said.

''We've worked to convince the people at Robins that, together, these two companies have a much better chance of success,'' Cawthorn said. He told them that Robins ''has a much better chance of coming out of Chapter 11 bankruptcy, effectively, quickly, strongly, by coming together with us while avoiding what they desperately want to avoid -- getting broken up, lost in a big company or just disintegrated.''

Cawthorn also told Robins officials ''that we're similar-size companies with similar heritage.'' And, he said, Rorer has ''a pretty good track record for putting organizations together in a sensitive way.''

In the end, those arguments worked -- those arguments and one other ingredient.

''He's had good luck too,'' said Gerald Rorer.