Certain proposed theories on second language acquisition, their justifications, and their predictions about English are examined in this paper. The first section discusses the process of second language acquisition; the stages and strategies learners use and progress through on their way to mastery are described. The second section discusses the order of acquisition and considers the question of whether there is a universal order. The final section discusses the similarities and differences between first and second language acquisition. The evidence shows that second language learners pass through universal stages and display similar strategies, indicating that second language acquisition is a creative process of rule formation, just like first language acquisition. The order of acquisition of linguistic structure is predicted mainly by variables within the target language, such as grammatical complexity, perceptual saliency, redundancy, and semantic weight and input. The differences between first and second language acquisition involve cognitive and environmental variables as well as interference. A bibliography is appended. (Author/NCR)