This study was conducted to determine the effects of biological science inquiry model and concept attainment model on students’ retention in Adamawa state, Nigeria. 3 objectives were stated; 2 research questions were raised and answered.  3 hypotheses were formulated and tested at 0.05 level of significance. A quasi-experimental research design involving non-randomized, pretest-posttest, experimental, control groups was employed. The population of this study included all year 2 (SS II) Senior Secondary Schools students in Adamawa state. A multistage sampling method was employed. 330 students from six intact classes of six secondary schools of Gombi education zone of Adamawa state were sampled out for the study. The instruments that was used for data collection was Biology Retention Test (BRT). The research questions were answered using descriptive statistics of mean and standard deviation while hypotheses were tested at 0.05 level of significance using two-way Analysis of Covariance (ANCOVA). Results of this study showed significant difference in the mean retention scores of students when taught biology using BSIM, CAM and lecture method, F = 10.76 (df 2, 329), P = 0.00; no significant difference in the mean retention scores of male and female students when taught biology using BSIM, CAM and lecture method, F =1.553 (df 1, 329), P = 0.214; no significant interaction effect of biological science inquiry model, concept attainment model, lecture method and gender on biology students’ retention in Adamawa State, F =0.523 (df 2, 329), P = 0.592;