This study aimed to investigate the effectiveness of self-questioning strategy in the development of mathematical word problem-solving skills for Grade Eleven students. To achieve this aim, a sample of (103) female students was selected from Grade Eleven, and was divided into two groups: an experimental group of (52) students, and a control group of (51) students. The two groups were checked for equivalence in each skill of the mathematical word problem-solving skills, specified in this study, and in the sum of these skills. After that, the experimental group was taught using the strategy of self-questioning while the control group was taught using the traditional teaching method. Data of the study was collected by the means of four tests prepared by the researcher to measure student skills in each phase of Polya's four phase approach to problem solving including understanding of the problem, devising a plan, carrying out the plan, and looking back. The four tests were checked for validity and reliability. The collected data of the study was analyzed using SPSS program to calculate means, standard deviations, and t-test. It was found that there is a statistical significant difference at the level of (a < 0.05) between the mean score of the experimental group and the mean score of the control group in favor of the experimental group in each one of the post-tests and in the test as a whole, and this difference was attributed to the strategy of self-questioning. In light of the results, the study recommended to benefit from the list of the word mathematical problems-solving skills and the self questioning strategy, which have been presented in this study, in the teaching of mathematical problem solving as well as in the development of the teacher's guide and textbooks of mathematics.