This paper examines disagreement over how second language learning tasks create conditions needed for language acquisition by exploring and comparing three second language acquisition theories: input-based; output-based; and interactionist. Each theory is described, and some new conclusions are drawn. It is argued that a task should: be meaningful; be cognitively appropriate; be fun; involve all participants in coming to a clear, defined conclusion; and allow for a planning stage. To accomplish the task, students need: support, through language boxes; different ways to say things; training in classroom feedback language; and pre-teaching. Contains 20 references. (MSE)