Although Legionella spp. live in a wide variety of freshwater habitats, they can be difficult to isolate. Culture and enumeration of Legionella from environmental sources involves several steps including concentration of the bacteria, resuspension, selective pre-treatments, and the use of complex media. Use of a suitable isolation protocol is critical for determining whether Legionella are present in a sample and at what concentration. The ELITE Program was created as a way for laboratories to test their Legionella isolation techniques against standardized samples. There is no charge for participating in the ELITE Program. Registration, results entry, and access to reports are available online. Participating labs receive a panel of lyophilized test samples biannually. The test samples are divided between Legionella positive or negative and may be mixed with other organisms commonly found in water. After reconstituting the test samples, participants process them according to their protocols and report their results. Labs that correctly identify Legionella from the test samples in two consecutive panels receive a certificate of proficiency and are listed among our ELITE Members. ELITE Program Members also have access to individualized performance reports, the latest CDC policies and guidelines, and CDC staff scientists to help optimize isolation procedures.