He was the author of 57 books (some under the pen name Robert Irving) about mathematics, science, and education, and the co-author of 30 more, for both children and adults.

His father, working first as a house painter, earned enough money to start a small business selling ice, coal, wood, seltzer, and prohibition beer (less than 1/2 of 1% alcohol).

After President Harry Truman issued an executive order in 1947 calling for loyalty investigations of federal employees, New York State adopted the "Feinberg Law" in 1949 providing for the dismissal of teachers who belonged to "subversive organizations".

Before the Feinberg Law was implemented, the New York Superintendent of Schools, William Jansen, began calling in teachers for questioning.

A book Adler wrote for adults in 1958, The New Mathematics,[11] was important in the "New Math" curriculum reform movement, and led to his frequent appearances at educational meetings throughout North America.

In 1959, Irving and Ruth Adler together began writing "The Reason Why" series of books about scientific concepts for elementary school children.

Later that year, Irving Adler married Joyce Sparer, a long-time family friend who had been teaching in Guyana.

After the death of Joyce's daughter Ellen, her three children came to live with them in Shaftsbury in 1977, and Adler retired from writing full-time.

In 1984, the Adlers embarked on an around-the-world lecture tour, speaking at universities in Australia, New Zealand, and several countries in Asia, and Europe.

In the late 1970s, Adler turned his attention to the question of phyllotaxis, specifically to the arrangement of plant spirals according to the Fibonacci sequence.