The purpose of this study is to evaluate the safety and immune response of a conjugated pneumococcal vaccine compared to a licensed 23-valent polysaccharide pneumococcal vaccine in elderly adults. Study participants will include 180 adults, 65 years of age or greater. Participants will be randomly assigned to 1 of 3 possible groups. Subjects will maintain a study diary to record side effects and oral temperatures for 7 days following each vaccination. Blood samples will be collected before and 1 month following each dose of vaccine or placebo. Participants will be involved in study related procedures for up to 268 days.