The primary purpose of this study was the naturalistic assessment of growth in oral English proficiency of Hispanic American limited English proficient (LEP) students in a paired reciprocal learning format. Subjects were fifth-grade students in a summer English-as-a-Second-Language class. Twelve students in a paired learning format and 12 in a nonpaired format were evaluated in 4 weekly language samples with the Naturalistic Assessment of Oral English Proficiency (NAOEP) instrument developed for the study. The instrument contained eight language items for assessment and used a coding sheet for other significant data. Time series repeated measures analysis was used to detect significant changes in language growth. The NAOEP instrument exhibited acceptable interrater reliability but generally low score stability week-to-week. The instrument was not successful in determining language growth, specifically for the paired group, which demonstrated few gains on any variable. The naturalistic oral language assessment of LEP students appears to require a substantial number of classroom observations and a versatile language assessment instrument. Three tables, three figures, and a chart present study findings. (Contains 27 references.) (SLD)