This study investigated the effects of two instructional approaches -- Discovery Learning Scientific Community Laboratories (DL-SCL; Treatment) and non-DLSCL laboratories (Control) -- on students' conceptual understanding, epistemological views, and academic achievement in a Physics-1 lab. Conceptual understanding was measured pre/post using the Mechanics Baseline Test (MBT) and the Force Concept Inventory (FCI). Epistemological views were measured pre/post using the E-CLASS (Zwickl et al., 2014). Lab scores and final exam scores served as measures of academic achievement. This study used a quasi-experimental study design with mixed-methods data collection and analysis procedures. Sections of a Physics-1 Lab course in Fall 2016 were assigned to three groups: Treatment (5 sections), Control (4 sections), and Traditional (3 sections). The study was conducted in three phases: (1st and 3rd) all three groups completed the same three initial and same three final experiments; and (2nd) Treatment sections were exposed to the DL-SCL approach and Control sections to the non-DL-SCL approach in the middle five experiments. Research question one (RQ1) focused on preexisting group differences, RQs 2 - 4 on group differences on each dependent measure, and RQ5 on the influence of demographic, parental, and experiential factors on study results. For RQ1, the only pre-existing difference was that average lab scores for the Traditional group differed from those of the Treatment and Control groups. For RQ2, Treatment group lab scores were significantly higher than for the Control group. For RQ3, on the MBT, Treatment group average normalized gain scores were significantly higher than for the Control group. For RQ4, E-CLASS results indicated that there was no significant difference between Treatment and Control students on either their personal epistemology (pretest or posttest) or their professional epistemology (pretest or pretest). For RQ 5, specific independent variables in all three sets -- demographic, parental, and academic factors -- significantly contributed toward explaining results on all five dependent measures. Study findings indicated that DL-SCL approach in teaching Physics Lab-1 significantly improved students' conceptual understanding, performance on labs and the final exam, but not their epistemological views. Student feedback survey, and personal interviews indicated that the DL-SCL improved students' interest in learning physics. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]