This study investigated the effects of inquiry strategy on upper basic II students’ problem-solving skills and achievement in Social Studies in Darazo Bauchi State. It also examined the interactive effect of inquiry strategy on gender. Quasi- experimental design of pre-test and post-test was adopted for the study. Two schools were randomly selected and the sample consisted of 84 upper basic II students comprising 48 males and 36 females from the two sampled schools. One of the two schools was designated experimental group and the other the control group through simple random sampling. Data were collected using Social Studies Problem-Solving Questionnaire (SSPSQ) and Social Studies Achievement Test (SOSAT). The SSPSQ consisted two sections A and B, section A consisted of respondents personal information and section B, consisted of 50 questionnaire items. SOSAT consisted of two sections. Section A consisted of particulars of respondents, section B consisted of 30 achievements test items. Construct validity was used to established the validity of SSPSQ and reliability was estimated using test-retest technique. SOSAT validity was ascertained by subjecting it to expert scrutiny and reliability was estimated using Cronbach Alpha. Three research questions and three hypotheses were formulated to guide the study, mean and standard deviation were used to answer all research questions while ANOVA was used to test the hypotheses at 0.05 level of significance. The study revealed that using inquiry strategy in teaching Social Studies significantly improved student’s problem-solving skills and achievement. It also found that no significant difference between the mean achievement scores of male and female students taught Social Studies using inquiry strategy. It is therefore recommended that Social Studies teachers should be trained on the use of inquiry strategy and also encouraged to embrace the use of inquiry strategy so as to improve problem-solving skills and achievement of students in Social Studies.