Political action committees (PACs) are one of the constants of American campaign finance. From the time of their rise to prominence in the mid-1980s, PACs increased in number and activity, leveling off by the end of the 1980s at around 4,000 federally registered PACs.1 PACs accounted for around 34% of the hard dollars reported by congressional races in the 2006 election cycle, around $320 million. PAC contributions have remained very stable in the mix among all types of contributions to candidates for Congress. Since 2000, they have stood between 33 and 34% of total contributions to congressional candidates.2