This study aimed to investigate the effect of WebQuests on improving eighth grade students' vocabulary achievement.Also, it aimed to investigate students' attitudes towards using WebQuest in learning English and the challenges they face while using it. The study was conducted as a quasi-experimental design consisted of two groups: the experimental group that was taught with WebQuest from Wilayyat BidBid School and the control group, which was taught with the conventional method, from Zainab bint Qais School. These conveniently selected schools are public and they are Cycle 2 schools in Dakhiliyya Governorate. The population of the study was all grade eight students in Dakhiliyya Governorate while the study sample was 60 female students: 30 of them were in the experimental group and the other 30 were in the control group. Both groups were randomly selected from a pool of 8 grade eight classes in both schools. Two instruments were used to collect data for this study. They were the vocabulary achievement test that was used as pre and post-test for both groups in order to answer the first research question. The second instrument was a student attitude questionnaire that was administered to the experimental group after the intervention to investigate students' perception about the efficacy of WebQuest, as an instructional strategy, in learning English and the challenges they face while using it. The main findings of the study are the following: Therewas a significant difference between the experimental group and the control group in the vocabulary achievement post-test scores in favor of the experimental group. The participants in the experimental group held highly positive attitudes towards using WebQuest in learning English. The participants faced some challenges in using WebQuest such as: The complexity of authentic reading, group-work misalignment, Internet unavailability, time constraints and lack of note-taking skills. Based on the findings of the study, the researcher recommended the necessity of implementing WebQuest as an instructional strategy in teaching English in the Sultanate of Oman. In addition, she recommended some suggestions for the development of the current study through further research.