It's been theorized that Thimerosal, a mercury-containing preservative found in many immunization vaccines, is linked to autism. Read the CDC's official stance here.

The Institute of Medicine, part of the National Academy of Sciences, rejects a causal relationship between immunizations and autism. Order the full report here.

A handful of scientific studies suggest a link between measles, mumps and rubella (MMR) immunizations and autism; find a partial list here.

Thimerosal, the ingredient in immunizations often thought to be linked to autism, is a non-toxic form of mercury called ethylmercury. Read a physician's explanation.

Much of the recent debated link between immunizations and autism comes from this leading advocacy group. Read their theories here, and decide for yourself.

The link between immunizations and autism was widely popularized by a major study published in 1998. In 2004, the authors of that paper retracted their stance.

Wondering what ingredients are in an immunization shot? This handy chart breaks down the ingredient list of many popular vaccines.

Some people believe that immunization unnecessarily puts children at risk for disorders such as autism. Add your thoughts to this forum discussion.

Common childhood diseases have been on the decline with the introduction of vaccines. Read answers to common questions, including those about immunizations and autism, here.

Looking for more information on thimerosal in vaccines? This FDA page explains how ingredients are evaluated and much more. Check out the links to the original medical studies here.