This paper illustrates the advantages of laboratory research into SLA by describing two studies of acquisition of second language syntax. The first addresses the question of whether human morphological abilities can be understood in terms of associative processes or whether it is necessary to postulate rule-based symbol processing systems underlying these skills. We demonstrate that acquisition of L2 morphology shows frequency effects for both regular and irregular forms and that the acquisition course of learners' accuracy and reaction time can be accurately simulated by connectionist systems. The second concerns a bootstrapping account of SLA whereby processes of chunking in phonological memory underpin the acquisition of long-term memory for utterances and abstractions of grammatical regularities. It shows that phonological short-term memory is particularly important in the acquisition of long-distance dependencies. In both cases, it is argued that these aspects of SLA reflect associative learning processes. When SLA research is properly focused on acquisition, laboratory research allows investigation of the learners' exposure to evidence, their processes of perception and learning, and their resultant language representations.