This may surprise some people but the Jan. 25 demonstrations that touched off Egypt's rebellion were anything but spontaneous. They were carefully organized by an opposition coalition, led by the April 6 movement - a secular organization dominated by young people. The movement originated three years ago, when it organized a day of protests and strikes; its Facebook group has nearly 90,000 members. April 6 is one of several broad secular coalitions that formed in recent years to promote democracy in Egypt. Another, led by former U.N. nuclear energy official Mohamed ElBaradei, has more than 240,000 Facebook members.

Over the weekend, most of the secular opposition groups and the banned Muslim Brotherhood met to form a joint platform. They called for Tuesday's mass demonstration and worked toward consensus on a platform. This probably will call for a transitional government, possibly headed by Mr. ElBaradei, that would lift political restrictions and lay the groundwork for free and fair elections. The coalition contains business owners, former members of parliament and defectors from the regime, and it has the capacity to oversee a political transition.

The Muslim Brotherhood remains Egypt's best-organized opposition political movement, but so far it has played a marginal role in the demonstrations. Its long-term aim of establishing an Islamic government in Egypt is at odds with what the mostly secular and middle-class demonstrators have been calling for, which is the democratization and modernization of the country. The Brotherhood, unlike its Palestinian offshoot Hamas, abandoned violence decades ago.

No one knows how the Islamists would fare in a free election, since one has not been held in Egypt during the past half-century. But many Egyptian analysts believe an Islamist party would attract a minority of voters and would be unlikely, in the short term, to come to power. In the longer term, the best defense against it is well-organized and dynamic secular parties - which will only be possible if the current authoritarian regime is dismantled.