The paper presents the results of a quasi-experimental study which was conducted with a view to determining the effect of an intervention in the form of the application of teacher-designed Internet-based resources (i.e., websites, podcasts, movie clips) that students could use autonomously on the development of pronunciation of the English regular past tense "-ed" ending. The sample consisted of 45 Polish secondary school learners. Participants were divided into three groups, two treatment and one control. The intervention spanned two weeks. The lessons in treatment group 1 were conducted by means of online resources and those in treatment group 2 were carried out in a traditional way (i.e., without autonomous recourse to computer-assisted pronunciation teaching). The students in the control group did not receive any instruction related to the pronunciation feature in question over that time. The data were gathered by means of perception and production tests administered before (pretest) and after (immediate and delayed posttests) the treatment, and subjected to quantitative analysis. The results, supported by the participants' evaluation of the two types of pedagogic intervention, indicate that although the effects of the experimental treatments proved to be comparable, the use of online resources produced more durable gains and was more favorably evaluated by learners. This provides a rationale for using computer technology as a tool for enhancing traditional teaching of English pronunciation in secondary school.