This study aimed to investigate the effect of using an instructional program based on self-regulated learning on the acquisition of algebraic concepts and creative thinking among students of the second cycle of basic education in the Sultanate of Oman with different mathematics self-efficacy. The study used a quasi-experimental approach with two groups and pre- and post-measurements, and its sample consisted of (99) students in the ninth grade. The sample was divided into two groups: an experimental group of (53) students, taught according to the instructional program based on self-regulated learning, and a control group taught as per the ordinary method. To achieve the objectives of the study, the researcher prepared a set of tools, which were: an acquiring algebraic concepts test, a mathematical creative thinking test, and a mathematics self-efficacy scale. The validity and reliability of these tools were extracted using appropriate methods, and they were found to be acceptable for the objectives of the study. To answer the study questions and test its hypotheses, Two-way ANCOVA was used and for more details, multivariate analysis of covariance (MANCOVA) was conducted. The results showed a statistically significant difference at (α = 0.05) in both acquiring algebraic concepts and its levels, and mathematical creative thinking and its skills due to the teaching method, in favor of the experimental group. Also, the results showed that there was a statistically significant difference at (α = 0.05) in both acquiring algebraic concepts and its levels, and mathematical creative thinking and its skills due to mathematics self- efficacy, in favor of high mathematics self –efficacy. The results also showed no statistically significant differences at (α = 0.05) in both acquiring algebraic concepts and its levels, and mathematical creative thinking in and its skills, due to the interaction between teaching methods and level of mathematics self- efficacy. In light of these results, the study recommended to including the proposed instructional program, based on self-regulated learning, in teachers’ professional development programs and encouraging them to use it. The study also, suggested conducting further researches to investigate the effect of using instructional programs based on self-regulated learning in teaching mathematics, in different variables, school cycles and grades, and content.