In order to interpret a sentence, hearers must often access information that is not explicitly stated, drawing on pragmatic knowledge and/or the discourse context. A problem with previous work on the acquisition of English focus particles such as "only," "also," "even," etc. is that it has often ignored such factors. Using a context-based methodology, this dissertation revisits English-speaking children's comprehension of sentences containing the focus particle "only" or "even," each of which requires special interpretive strategies. The author's dissertation consisted of four experiments, drawing on different methodologies, but each makes crucial use of context. Experiments 1 and 2 explored how English-speaking children aged 4 to 5 interpret sentences containing "only," using a Truth Value Judgment task. Experiments 3 and 4 investigated English-speaking children's construal of sentences containing "even" in terms of scalar implicature. Understanding sentences containing focus particles requires the establishment and integration of knowledge from different domains, including syntax (how to identify the target of focus), semantics (the meaning of focus particles), and pragmatics (computation of contrast sets and of implicature). The experiments reported in the author's dissertation thus contribute to research on children's ability to integrate syntactic, semantic, and pragmatic knowledge at the "interfaces" in the course of sentence interpretation.