Six experiments explored how native and non-native Spanish speakers process article-noun sequences in real time, using eye movements as a response measure. Can listeners use gender-marked articles ("la" and "el", the feminine and masculine forms of "the") to rapidly identify familiar and novel nouns? In Experiment 1, adults who learned Spanish as a first language (L1 adults) or second language (L2 adults) viewed familiar objects with names of either the same (e.g., "pelota", "ball" [subscript [f]], "galleta", "cookie" [subscript [f]]) or different grammatical gender ("pelota", "zapato", "shoe" [subscript [m]]) while listening to Spanish sentences that referred to one object ("Encuentra la pelota", "Find the ball"). L1 adults, but not L2 adults, oriented to the target more rapidly on different-gender trials, when the article was informative about the identity of the referent. Two word-learning experiments explored whether frequency of exposure to article-noun pairs could account in part for L1-L2 differences in processing efficiency. L1 and L2 adults learned names for novel objects in sentences with either definite articles (Experiment 2) or indefinite articles (Experiment 3), and then heard sentences with definite articles that referred to one of two objects. When definite articles were used throughout the experiment, L1 and L2 adults initiated eye movements to target pictures significantly faster on different-gender trials. But L2 adults did not exploit gender information when different articles were used in teaching and testing. Experiments 4 and 5 explored the processing of article-noun sequences that conveyed perceptually accessible features of referents, such as natural gender (e.g., "Encuentra la nina", "Find the girl" [subscript [f]]) or number (e.g., "Encuentra los pajaros", "Find the birds"). L1 and L2 adults successfully took advantage of informative articles in both cases. Experiment 6 extended these experiments to investigate language processing by two additional participant groups: native Spanish-speaking children in elementary school (L1 children) and native English-speaking children learning Spanish in elementary school immersion programs (L2 children). Preliminary results reveal both differences and similarities in how L1 and L2 children process cues to grammatical gender, natural gender, and number. Experience-related factors are used to interpret how L1 and L2 learners--who learned Spanish at different ages and in different settings--understand article-noun sequences. [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.]