This dissertation study investigated the effects of oral corrective feedback (CF) in the form of prompts and recasts (Ammar, 2008; Ammar & Spada, 2006; Lyster, 2004; Lyster & Izquerdo, 2009) on second language (L2) vocabulary development (de la Fuente, 2002; Ellis & He, 1999; Ellis, Tanaka, & Yamazaki, 1994). A population of intermediate adult learners of English as a second language (ESL) in a community college located in the US Southwest was used.

The quasi-experimental study used pretest-posttest-delayed posttest design. The participants (n = 23) were conveniently selected and designated to three groups: prompts, recasts, and control. The treatment consisted of a four-step vocabulary activity during which prompts, recasts or no feedback was provided, respectively. The treatment outcomes were tested in terms of measures based on an adaptation of a three-dimensional second language vocabulary development model (Henriksen, 1999, 2008) and in-group proficiency. Data includes treatment session transcriptions, a revised and combined 2000/University Word Level Test (Beglar & Hunt, 1999), pretest, posttest, delayed posttest, and longer-delayed posttest, plus a background questionnaire. Repeated Measures Analysis of Variance (RM ANOVA), Repeated Measures Multivariate Analysis of Variance (RM MANOVA), correlations, plus pair-samples t-tests and multiple and linear regressions were conducted to analyze the results.

The findings appear to indicate that prompts were equally beneficial in short term and slightly more advantageous in a longer term than recasts in facilitating L2 vocabulary development for community college adult ESL learners. However, from both CF groups, only the prompts group demonstrated significant increases on all three dimensions of L2 vocabulary development as they were operationalized for this study.