Louise Hay, who from a 1984 best seller built a self-help publishing empire that has attracted millions of devotees with its messages about the power of thought and attitude, died on Wednesday at her home in San Diego. She was 90.

Her death was announced on the website of her company, Hay House. In books like “You Can Heal Your Life,” “The Power Is Within You” and “Meditations to Heal Your Life,” Ms. Hay espoused an upbeat message with a metaphysical underpinning. She wrote that there is a link between thoughts and disease and life’s other misfortunes, and she urged people to find a positive way to spin even the worst of them.

In 1985, at a time when fear of AIDS was high and those who had it were being shunned by much of society, Ms. Hay, by now relocated to the West Coast, began holding support meetings for people living with H.I.V. or AIDS. The first sessions were in her home.

“I said, ‘I have no idea what we’re doing, but I know what we’re not going to do,’ ” she recalled in 2008. “ ‘We’re not going to play Ain’t it awful.’ ”

Eventually the sessions, called Hayrides, were moved to an auditorium in West Hollywood, with hundreds in attendance, including mothers of those with the disease.

“Whenever a mother came, we gave them a standing ovation, because so many mothers weren’t speaking to their sons,” she said. What of the fathers? “The fathers almost never came — they couldn’t forgive.”