RIYADH, Saudi Arabia — Hackers defaced their Web site. Delegations of clerics appealed to the king to block their movement. And men claiming to be security agents called their cellphones to leave a clear message:

O, women of the kingdom, do not get behind the wheel!

But they did anyway. On Saturday, a few dozen women insisted on violating one of the most stubborn social codes in staunchly conservative Saudi society, getting into their cars and driving, activists said. Many posted videos of themselves doing so to spread the word.

“We are looking for a normal way of life,” Madiha al-Ajroush, 60, a psychologist, said in an interview in Riyadh, the Saudi capital, “for me to get into my car and do something as small as get myself a cappuccino or something as grand as taking my child to the emergency room.”

The public call for women nationwide to drive on Saturday was the latest push in a decades-old effort by a small group of activists to exercise what they see as a fundamental human right. Saudi Arabia, a hereditary monarchy, is the only country in the world where women are not allowed to drive.

The fact that the activists have been at it for so long without creating a mass movement or any change in government policy underlines the power of tradition in Saudi society and the tremendous political clout of social conservatives who fear that Westernization or anything that looks as if it will detract from the kingdom’s Islamic character, even though malls, high-end shops and fast-food outlets cover the Saudi landscape.