"There's no silver bullet," she said, when it comes to fighting Internet censorship and blocking. "There's no app for that."
Calling Internet freedom a "foreign policy priority," Clinton's speech represents the Obama administration's biggest push yet to support global access.
The remarks follow Internet crackdowns across the Middle East, including an attempted full-scale blackout in Egypt during protests there this year.
The Internet, Clinton said, is the "public square" of the 21st century. She made the case for dialoguing with other nations on what's acceptable practice.
That includes discussions on "what rules exist and do not exist and why," and "what behaviors should be encourages or discouraged and why."
Clinton described the the Internet as an engine for economic growth and said countries who fail to get on board will pay in lost opportunities.
She listed Internet freedom violations worldwide, including denial of service attacks on news sites in Burma, an attempt to create an insular Cuba-only intranet, the arrests of bloggers in Vietnam. She also took a firm stance against Internet crackdowns in Iran.