Previous literature shows that language input is related to the language that children produce. Less is known about how the input provided to children relates to the way that they process language. In this study, this question was explored by looking at the relationships between children's word learning ability and the kinds of names provided by parents for objects. Whether these relationships varied with age and vocabulary size was also investigated. Children from five age groups at 12-, 16-, 20-, 24-, and 28-months participated in two types of tasks. First, to characterize the amount and type of labels used by parents, parents and children were videotaped in a naturalistic play in which they played with four sets of familiar and unfamiliar toys. Second, to characterize the children's ability to learn new labels, children were taught and tested on their learning of new words for familiar and unfamiliar objects either directly or indirectly (i.e. by inference). A factor analysis of parent's contrasts of multiple labels for the same object showed that the input was consistent with several factors suggested to influence children's successful learning of labels including the taxonomic level of the label, whether the name is for a whole object or a part, and whether the label is for a familiar or unfamiliar object. In the word learning task, children learned labels for familiar and unfamiliar objects equally well following direct teaching, but learned labels for unfamiliar objects easier following indirect teaching. The types of contrasts provided by parents were related to children's abilities to learn multiple names for objects such that parents' use of taxonomic contrasts was related to children learning more multiple names. Age and vocabulary size could not account for these relationships. These results suggest that the input provided by parents is related to several word learning principles put forth in previous literature. In addition, this input is related to children's performance in a word learning task. The implications for understanding several word learning processes are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]