While many parents have heard the rhetoric that vaccines are safe and effective and that the science is settled about the relationship between vaccines and autism, few realize that in the 1960s, American children received three vaccines compared to the thirty-eight they receive today. Or that when parents are told that the odds of an adverse reaction are “one in a million,” the odds are actually one in fifty. Or that in the 1980s, the rate of autism was one in ten thousand children. Today it’s one in thirty-six.