这本书用简洁的语言概述了第二语言习得的研究状况，通俗易懂，对于刚入门的读者来说会有很大帮助。我认为该书在编排上最大的优点是在书的末尾有与正文有关的一些小案例，可以帮助读者更好的理解和掌握作者在书中讲到的理论。在读完这本书后，我自己感觉收获颇丰。
          ——Second Language Acquisition（Rod Ellis, 上海外语教育出版社）
1. What’s ‘Second Language Acquisition’?
1) Introduction: describing and explaining L2 acquisition
L2 is fairly a recent phenomenon, belonging to the second half of the twentieth century. ‘L2 acquisition’ can be defined as the way in which people learn a language   other than their mother tongue ,inside or outside of a classroom, and Second Language Acquisition (SLA) as the study of this.
2) What are the goals of SLA?
In general, SLA has not focused on the communicative aspects of language development but on the formal features of language that linguists have traditionally concentrated on. One of the goals of SLA description of L2 acquisition. Another is explanation : identifying the external and internal factors that account for why learners acquire an L2 in the way they to . One of the external factors is the social milieu in which learning takes place. Another external factor is the input that learners receive, that is , the samples of language to which a learner exposed.
The internal factors are as follows: (1) Learners possess cognitive mechanisms which enable them to extract information about the L2 from the input ;(2)L2 learners bring an enormous amount of knowledge to task of learning an L2；（3）L2 learners possess general knowledge about the world which they can draw on to help them understand L2 input; (4) L2 learners possess communication strategies that can help them take effective use of their L2 knowledge.
The goals of SLA , then , are to describe how L2 acquisition proceeds and to explain this process and why some learners seem to be better at is than others.
2. The nature of learner language
1) The main way of investigating L2 acquisition
The main way of investigating L2 acquisition is by collecting and describing samples of learner language . The description may focus on the kinds of errors learners make and how these errors change over time, or it may identify developmental patterns by describing the stages in the acquisition of particular grammatical features such as past tense, or it may examine the variability found in learner language.
2) Errors and error analysis
(1) The first step in analyzing learner errors is to identify them. It is difficult to identify errors because of two reasons: firstly, it is often difficult to identify the exact errors that learners make. secondly, it’s hard to distinguish errors and mistakes.
(2) The second step is describing errors. Once all the errors have been identified , they can be described and classified into types. There are several ways of doing this . One way is to classify general ways in which the learners utterances differ from the reconstructed target-language utterance. Such ways include ‘omission’, ‘misinformation’ and ‘disordering’.
(3) Explaining errors: the identification and description of errors are preliminaries to the much more interesting task of trying to explain why they occur.
(4) Error evaluation
3) Development patterns
(1) The early stages of L2 acquisition : in the circumstances which L2 learners learn a language as a natural, untutored process, they undergo a silent period. When learners do begin to speak in the L2 their speech is likely to manifest two particular characteristics. One is the kind of formulaic chunks. The second characteristic of early speech is propositional simplification.
(2) The order of acquisition: accuracy order and the order of acquisition
(3) Sequence of acquisition
4) Variability in learner language
Learner’s language is systematic, but it is also variable. These two characteristics are not contradicted because it is possible that variability is also systematic.
(1) It appears that learners vary in their use of the L2 according to linguistic context.
(2) Learners also vary the linguistic forms they use in accordance with the situational context.
(3) Another important factor that accounts for the systematic nature of variability is the psycholinguistic context.
But it would seem that at least some variability is ‘free’. Learners do sometimes use two or more forms in free variation.
3. Interlanguage
1) Behaviorist learning theory
2) A mentalist of language learning
In the 1960 and 1970 , a mentalist theory first language (L1) acquisition emerged. According to this theory:
(1) Only human beings are capable of learning language.
(2) The human mind is equipped with a faculty for learning language, referred to as a Language Acquisition Device. This is separate from the faculties responsible for other kinds of cognitive activity ( for example, logical reasoning).
(3) This faculty is the primary determinant of language acquisition
(4) Input is needed, but only to ‘trigger’ the operation of the language acquisition device.
The conception of interlanguage drew directly on these mentalist views of L1 acquisition.
3) What’s ‘interlanguage’?
The term ‘interlanguage’ was coined by the American linguist, Larry Selinker, in recognition of the fact that L2 learners construct a linguistic system that draws, in part, on the learner’s L1 but it also different from it and also from the target language. A learner’s interlanguage is, therefore, a unique linguistic system.
The concept of interlanguage involves the following premises about L2 acquisition:
(1) The learner constructs a system of abstract linguistic rules which underlies comprehension and production of the L2. This system of rules is viewed as a ‘mental grammar’ and is referred to as an ‘interlanguage’.
(2) The learner’s grammar is permeable.
(3) The learner’s grammar is transitional.
(4) Some researchers have claimed that the systems learners construct contain variable rules.
(5) Learners employ various learning strategies to develop their interlanguages.
(6) The learner’s grammar is likely to fossilize.
4)A computational model of L2 acquisition

Input →intake→L2 knowledge →output
4.Social aspects of interlanguage
Three rather different approaches to incorporating a social angle on the study of L2 acquisition can be identified. The first views interlanguage as consisting of different ‘styles’ which learners call upon under different conditions of language use. The second concerns how social factors determine the input that learners use to construct their interlanguage. The third considers how the social identities that learners negotiate in their interactions with native speakers shape their opportunities to speak and, thereby , to learn an L2.
1) Interlanguage as a stylistic continuum
Drawing on work on variability in learner language, Elaine Tarone has proposed that interlanguage involves a stylistic continuum.
Another theory that also draws on the idea of stylistic variation but which is more obviously social is Howard Gile’s accommodation theory.
2) The acculturation model of L2 acquisition
A similar perspective on the role of social factors in L2 acquisition can be found in John Schumann’s acculturation model.
3) Social identity and investment in L2 learning
The notions of ‘subject to’ and ‘subject of’ are central to Bonny Peirce’s view of the relationship between social context and L2 acquisition.
5  Discourse aspects of interlanguage
The study of learner discourse in SLA has been informed by two rather different goals. On the one hand there have been attempts to discover how L2 learners acquire the ‘rules’ of discourse that inform native-speaker language use. On the other hand, a number of researchers have sought to show how interaction shapes interlanguage development.
1) Acquiring discourse rules
2) The role of input and interaction in L2 acquisition
(1) According to Stephen Krashen’s input hypothesis, L2 acquisition takes place when a learner understands input that contains grammatical forms that are at ‘i+1’. According to Krashen , L2 acquisition depends on comprehension input.
Michael Long’s interaction hypothesis also emphasizes the importance of comprehensible input but claims that it is most effective when it is modified through the negotiation of meaning.
(2) Another perspective on the relationship between discourse and L2 acquisition is provided by Evelyn Hatch. Hatch emphasizes the collaborative endeavors of the learners and their interlocutors in constructing discourse and suggests that syntactic structures can grow out of the process of building discourse.
(3)  Other SLA theorists have drawn on the theories of L.S. Vygotsky, a Russian psychologist , to explain how interaction serves as the bedrock of acquisition.
3) The role of output in L2 acquisition
Krashen argues that ‘Speaking is the result of acquisition not it’s cause’. In contrast, Merrill Swain has argued that comprehensible output also plays a part in L2 acquisition.
6  Psycholinguistic aspects of interlanguage
1) L1 transfer
It is clear that the transfer is governed by learners perceptions about what is transferable and by their stage of development.
2) The role of consciousness in L2 acquisition
Stephen Krashen has argued the need to distinguish ‘acquired’L2 knowledge and ‘learned’ Ls knowledge . He claims that the former is developed subconsciously through comprehending input while communicating, while the latter is developed consciously through deliberate study of the L2.
Richard Schmidt has pointed out that the term ‘consciousness’ is often used very loosely in SLA and argues that there is a need to standardize the concepts that underlie its use.
Schmidt argues that no matter whether learning is intentional or incidental, it involves conscious attention to features in the input.
3) Processing operations
(1) Operating principles
The study of the L1 acquisition of many different languages has led to the identification of a number of general strategies which children use to extract and segment linguistic information from the language they hear. Dan Slobin has referred to these strategies as operation principles. Roger Anderson describes a number of operating principles for L2acquisition, and he claims that his principles are ‘macro principles’.
4) Processing constraints
5) Communicative strategies
6) Two types of computational model
 One type involves the idea of ‘serial processing’. The alternative type of apparatus involves the idea of parallel distributed processing.
7. Linguistic aspects of interlanguage
1) Typological universals: relative clauses
A good example of how linguistic enquiry can shed light on interlanguage development can be found in the study of relative clauses.
2) Universal Grammar
Chomsky argues that language is governed by a set of highly abstract principles that provides parameters which are given particular settings in different languages.
3)learnability
Chomsky has claimed that children learning their L1 must rely on innate knowledge of language because otherwise the task facing them is an impossible one.
 4) The critical period hypothesis
 The critical period hypothesis states that there is a period during which language acquisition is easy and complete and beyond which it is difficult and typically incomplete.
5) Access to UG
  We will briefly examine a number of theoretical positions.
a) Complete access: An assumption is that full target-language competence is possible and that there is no such thing as a critical period.
b) No access : The argument here is that UG is not available to adult L2 learners.
c) Partial access: Another theoretical possibility is that learners have access to part of UG but not others.
d) Dual access
  According to this position, adult L2 learners make use of both UG and general learning strategies.
6) Markedness
7) Cognitive versus linguistic explanations
8. Individual differences in L2 acquisition
1) Language aptitude
  Early work by John Carroll led to the identification of a number of components of language aptitude. These are:
(1) Phonemic coding ability.
(2) Grammatical sensitivity.
(3) Inductive language learning ability.
(4) Rote learning ability.
2) Motivation
Various kinds of motivation have been identified: instrumental, integrative, resultative and intrinsic.
3) Learning strategies
 Different kinds of learning strategies have been identified.
 Cognitive strategies are those that are involved in the analysis, synthesis, or transformation of learning materials.
 Metacognitive strategies are those involved in planning, monitoring, and evaluating learning.
Social/ affective strategies concern the ways in which learners choose to interact with other speakers.
9.Instruction and L2 acquisition
Some researchers have studied what impact teaching has on L2 learning. In this chapter we will consider three branches of this research. The first concerns whether teaching learners grammar has any effect on their interlanguage development. The second draws on the research into individual learner differences. The third branch looks at strategy training.
1) Form-focused instruction
2) Does form-focused instruction work?
3) What kind of form-focused instruction works best?
Given that instruction can work, it becomes important to discover whether some kinds of instruction work better than others. To illustrate this we will consider a number of options in form-focused instruction. The first concerns the distinction between input-based and production-based practice.
The second issue concerns conscious-raising.
4) Learner-Instruction matching
A distinct possibility is that the same instructional option is not equally for all L2 learners.
5) Strategy straining
Most of the research on strategy training has focused on vocabulary learning.