New research on immigration brings some good news and a clear policy challenge. The good news is that after a steady decline in the percentage of eligible immigrants who opt to become citizens, the naturalization rate rose in the late 1990s. Despite high numbers and rising rates, however, a large pool of legal immigrants who could naturalize7.9 million total and 2.7 million in California alonehasn't done so. Nationally, another 2.7 million are coming on line for eligibility in the next several years.