This study presents a validation report of the Lecturer's Teaching Assessment Scale (LTAS) developed for the assessment of lecturer's teaching effectiveness in Obafemi Awolowo University, Ile-Ife, Nigeria. It also examined the factor structure of the LTAS, its construct validity, and internal consistency reliability coefficients. The study adopted the survey research design. A total of 13,000 students that completed the LTAS online constituted the sample for the study. The 34-item LTAS was used to collect data for the study. Collected data were subjected to reliability and factor analyses. Results showed that the LTAS has two subscales--Attitude to Teaching and Lecture Presentation and Organisation. The LTAS was adjudged to possess construct validity, and it was established through experts' judgement. The results also revealed that the LTAS was reliable (Cronbach Alpha reliability coefficient of 0.985, Spearman Brown's Split-half reliability coefficient of 0.998 and Gutman's Split-half coefficient of 0.997). Thus, the LTAS possessed adequate psychometric qualities that make it suitable for use among Nigerian undergraduate students.