When learning English, learners might face a challenging task in mastering pronunciation due to differences in both languages such as sound-to-letter correspondence, size of phoneme inventory, allophonic realization of sounds, place and manner of articulation, among others. Therefore, the purpose of this paper is to review both theoretical and research reports on the most problematic sounds for Spanish-speakers English language learners. Approaches to second language learners' errors like Contrastive Analysis and Error Analysis although being criticized have contributed to identifying likely causes of errors and dealing with them whether anticipating them or providing appropriate feedback on them. Besides, first language interference and age of second language acquisition have been found as complicating factors in the English pronunciation learning process. Finally, some classroom activities have been reported as successful for facilitating English pronunciation in Spanish native speakers.