To better understand humoral immunity against respiratory syncytial virus (RSV) and the role of serum antibodies to the surface fusion (F) glycoprotein in disease severity and protection, a large database consisting of collected sera and patient information was analyzed using plaque reduction neutralization and F antigen ELISA assays. Out of 73 infected and 73 non-infected infants with cardiopulmonary disease (matched for age and underlying disease), neutralizing antibody titers $\ge$1:100 and ELISA titers $\ge$1:10,000 were significantly correlated with a decreased incidence of RSV infection. The neutralization and ELISA assays also correlated highly when compared to each other. Acute sera samples from previously healthy infants for whom infecting subgroup was known (82 infected with subgroup A, 127 infected with subgroup B) were also analyzed as above, and an age $<$13 weeks was found to be significantly associated with severe RSV disease. As well, those infants infected with subgroup B, having an F ELISAtiter $>$1:1000 had a 5 fold less incidence of hypoxia, independent of age. Out of 45 subgroup A infected and 99 subgroup B infected infants and children for which paired acute - convalescent sera were collected, young age was significantly associated with a poor convalescent antibody response. For B infected infants only, neutralizing antibody titers $<$1:40 against subgroup B were significantly associated with a poor homologous response. Collectively, these results contribute to the understanding of humoral immunity to RSV.