The purpose of the study was to investigate "what students' work and explanation of their work would show about their development of structure sense and their algebraic proficiency after receiving structure-sense teaching for eight weeks in a community college precalculus algebra course." Structure sense is a group of abilities formally described by Hoch and Dreyfus (2004; 2006; 2007) to refer to recognition and use of structure when reasoning through algebraic statements. A review of the literature suggested that algebraic proficiency can be described on two levels: (a) a level pertaining to mathematics, in general and (b) a level pertaining to algebra in particular. The first level characterizes the broad processes and practices through which mathematical proficiency is shown according to CCSSM (2011), NCTM (2000), and NRC (2001). The second level of algebraic proficiency involves aspects that are more specific to the nature of algebra as described by Carlson et al.(2010), Driscoll (1999), Kieran (2007) McCallum (2007), and NRC (2001). In the quantitative strand, students' test scores showed improvement in structure sense and in algebraic proficiency. However, improvements in both areas needed to be unpacked. In the qualitative strand of the study, students' work and explanation of their work showed development of structure sense in various ways and more in some aspects than others. Their work also suggested other patterns. The results and analyses of the study have potentially important information for teaching and redesigning precalculus algebra courses. [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/en-US/products/dissertations/individuals.shtml.]