EFL teachers have always come across students who struggle to learn a foreign language and have great difficulty mastering it because of learning disabilities. Possible causes such as language aptitude, native language skills, affective variables such as anxiety, motivation and personality, lack of effort, poor language learning habits and low ability in language learning are among the factors which have been the concern of many researchers. Ehrman (1996) believes that “language is ambiguous and unpredictable” (p.57), and ambiguous situations are sources of threat for those who are intolerant of ambiguity (Budner, 1962, cited in Johnson, 2001). While learning a second or foreign language encompasses many occasions where apparently contradictory information is encountered such as words, structures, rules, and even the culture, the ability to tolerate ambiguity is considered as a key to language learning success. Moreover, Ehrman believes that learning styles mismatches are at the root of many learning difficulties. Attempts should be made to make the most of the L2 learner’s comfort zones, the style preferences, as well as cognitive styles which are the individual’s different style of forming concepts, solving problems and thinking. Besides these factors, since the absence of motivation, amotivation, in educational settings usually leads to boredom and poor concentration in class, poor psychological adjustment to the learning environment, high level of stress, and school dropout (Legault, Green-Demers, & Pelletier, 2006), it seems necessary to investigate it as one of the possible causes of failure in learning English as a foreign language. In addition, by considering Ryan and Deci’s (2000) self-determination theory which states that one’s behavior can be influenced by intrinsic motivation, extrinsic motivation and amotivaion, it seems appropriate to focus on various means to motivate language learners. Since recognition of learning disabilities as a problem and providing solutions for the students facing such a challenge and the teachers who teach them seems urgent, the present case study first reports some of the learning problems faced by an Iranian student in learning English as a foreign language, then from the many factors considered to be possible causes of learning disabilities, this study focuses on tolerance of ambiguity, impulsive cognitive style and motivation based on the results of a number of questionnaires and personal interviews with the learner. Finally, after mentioning the attempts made to help the learner to overcome the problems encountered in learning English, some effective instructional guidelines are suggested to help learners with learning disabilities to learn better.