This course provides a thorough examination of intelligence, its measurement, and the factors that influence cognitive performance. Beginning with foundational questions—what intelligence is and how it should be defined—students learn to evaluate different assessment methods and their reliability, validity, and practical applications. The course covers the history of intelligence testing, the development of IQ tests, and the distribution of intelligence across populations. Students will explore the genetic and environmental influences on IQ, including specific genes, group differences, sex differences, and racial disparities. The Flynn Effect and the role of environmental factors are analyzed to understand how intelligence can change over generations. The course also addresses psychological phenomena such as mindset, expectations, stereotype threat, and identity contingencies, which affect performance and perception of intelligence. Finally, learners examine whether IQ can be improved through interventions, strategies, and cognitive training. With review questions and practical examples, this course equips students with a comprehensive understanding of intelligence and its assessment, bridging the gap between theory, research, and real-world applications in psychology.