WHEN SHE decided to write a series of children's novels about an ordinary pre-teen named Alice, Phyllis Reynolds Naylor knew exactly what the focus would be.
''It's based on experiences I had when I was growing up,'' Naylor said. "The mortifying, excruciating embarrassments you don't want anyone to know about.''
The second book in the series, ''Alice in Rapture, Sort Of,'' follows Alice through the summer before seventh grade, also known as The Summer of the First Boyfriend. She struggles to cope with everything from her first nervous kiss to the trauma of her first frizzy perm.
Naylor's realistic portrayal of Alice has won this year's Hedda Seisler Mason Award, presented by the Enoch Pratt Free Library for the most significant children's book by a Maryland author.
Naylor, who lives in Bethesda, will receive the award this Saturday at 2:30 p.m. at the Pratt Central Library.
''Almost any child can identify with Alice,'' said Regina Wade, chairwoman of the award selection committee and assistant head of the children's department at the Pratt. ''We all felt that as seemingly light as parts of the book are -- and you do laugh a lot -- we came to feel that it was a very important book. A child who reads it can come away feeling that 'there's someone who feels exactly the way I do.' ''
Other members of the selection committee were Jeffrey Korman and Diana Valentine of the Pratt staff, Susan Deeney of the Harford County Public Library staff and Linda Lapides, a retired librarian who is also a noted collector of children's books.
''Written in a simple style, this story is packed with all the appropriate questions a young person must ask herself as she enters adolescence,'' Korman wrote in his review. ''Each sequence helps Alice evolve to the point that when finished the book, the reader knows her very well and likes her and her beliefs.''
Indeed, Alice's everyday worries and embarrassments have struck a chord with legions of fans. Many children have written to Naylor, sharing their own mortifying moments.
''One little girl wrote about the time she stuck a purple vitamin tablet up her nose and couldn't get it out,'' Naylor said. She spent the entire school day trying to pretend nothing was amiss.
''Alice in Rapture, Sort Of,'' published in 1989, is the second in a series that began with ''The Agony of Alice,'' in 1985 and continues in ''Reluctantly Alice,'' published this year. Naylor has already written ''All But Alice,'' which will come out next year, followed by ''Alice in April'' in 1993 and ''Alice in Between'' in 1994. All are or will be published by Atheneum.
Naylor, 58, has been writing full-time since 1960. In all she has written 75 books, including 12 that will be published in the next four years. She obviously likes to get ahead of herself.
Her works range from picture books to adult novels, and she has won more than a dozen awards for her children's and young adult books.
"I love writing more than anything else, but I also travel a great deal,'' she said. ''I enjoy giving speeches and I enjoy the feedback from audiences.'' She also makes the most of her time on the road, traveling by train whenever she can.
''I get a bedroom on Amtrak, and I can close the door and write all night long,'' she said. ''I'd hate to have it written that I go on speaking trips just to have my writer's retreat on Amtrak, but that's perhaps 50 percent of it . . . There's something about the rhythm of the wheels and the swaying of the coach that's hard to describe, but the words just come pouring out.''
The public is invited to the presentation of the Hedda Seisler Mason Award, this Saturday at 2:30 p.m. in the Poe Room of the Pratt Central Library, 400 Cathedral St.
Phyllis Reynolds Naylor will receive the 1991 award for ''Alice in Rapture, Sort Of.'' In addition, a special Honor Book award will be presented to Elizabeth Fitzgerald Howard, author of ''Chita's Christmas Tree.''
Both writers will autograph their books, copies of which will be available for purchase in the Poe Room. The Hedda Seisler Mason Award is presented every two years. It was established by former Evening Sun copy editor Franklin Mason in honor of his late wife, who was a children's librarian with the Pratt.