In this paper the impact of various factors on teacher effectiveness is considered in the South African context. The Teacher Effectiveness Model is constructed to answer the research question whether it is the low quantity of teachers or predominantly their low quality that contributes to the basic education crisis of Quintile 1 to 3 schools in the Western Cape, South Africa. The model illustrates the impact of improving the quantity and quality of teachers within the province. This research question is answered when the system exhibits an increase of 13% in the success measure when the quantity is improved and an increase of 10% in the success measure when quality is improved. Improvement in both factors, however, gives the best result with a 17% increase in the success measure.