This study investigated the relative effectiveness of Concept Mapping Strategy (CMS) and Guided Discovery Method (GDM) in enhancing students achievement in Physics. Gender influence on students achievement was also examined. A total of one hundred and fifteen (115) secondary school Physics students were involved in the study; the research work was carried out in the Wukari Education Zone of Taraba State. This research work adapted a quasi-experimental research design involving pre-test and post-test. Three research questions and three hypotheses were raised. Physics Achievement Test (PAT) was used for data collection. The items of PAT were subjected to item analysis. The reliability coefficient of the instrument was obtained using Kuder-Richardson 20 formula is .8. Mean and standard deviation was used to answer the research questions, while Analysis of Covariance was used to test the hypotheses formulated at .05 significance level. From the analysis, it is revealed that a statistically significant difference exists in the mean academic achievement scores of students taught physics using CMS and those taught using GDM in favor of CMS. Gender differences are not statistically significant in the mean academic achievement scores for both CMS and GDM groups. It is evident from the findings of this study that the use of CMS could provide a good way for students to learn Physics. It is recommended, based on the findings of the study, that Physics teachers should be encouraged to use a CMS while teaching Physics concepts to actively involve the students in identifying relationships in concepts. Government should utilize the services of various professional bodies like the Science Teachers Association of Nigeria (STAN) in collaboration with the Nigeria Educational Research and Development Centre (NERDC) to organize seminars, workshops, conferences, in-service training and symposia to inform and train physics teachers on the use of innovative teaching method especially concept-mapping.