This thesis consists of three empirical studies. The first study, Rationales to Language-in-Education Policies in Postcolonial Africa: Towards a Holistic Approach, considers two issues. First, it explores the factors affecting the choice of an LiE policy in 35 African countries. The results show that the countries adopting a unilingual education system put different weights on the influential parameters than countries adopting a bilingual education system. Second, the study investigates how decision makers can ensure the optimal choice of language(s) of instruction by developing a non-cooperative game theoretic model with network externalities. The model shows that it is never optimal for two countries to become bilingual, or for the majority linguistic group to learn the language of the minority group, unless there is minimum cooperation to ensure an equitable redistribution of payoffs. The second study, The Role of Language in Learning Achievement: A Namibian Case Study, investigates the role played by home language and language proficiency on SACMEQ II mathematics scores of Namibian Grade-6 learners. HLM is used to partition the total variance in mathematics achievement into its within- and between-school components. Results show that although home language plays a limited role in explaining within- and between-school variations in mathematics achievement, language proficiency (proxied by reading scores) plays a significant role in the heterogeneity of results. Finally, the third study, Language Skills and Economic Returns, investigates the economic returns to language skills, assuming that language competencies constitute key components of human capital. It presents results from eight IALS countries. The study finds that in each country, skills in a second language are a significant factor that constrains wage opportunities positively.