According to the National Clearinghouse on Autism Evidence and Practice, ABA is an evidence based intervention. Evidence based means that ABA has passed scientific reviews of its uses, its effectiveness and if it can be replicated. ABA Therapy includes many different techniques.  All of these techniques focus on antecedents (what happens before a behaviour occurs) and on consequences (what happens after the behaviour).  More than 20 scientific articles have been published that have proven that ABA is effective. Most of the research has focused on intensive, long term programs (40+ hours/week of therapy for 2+ years). However there is newer research coming out that demonstrates very clearly that focused ABA (limited number of hours each week for a shorter duration) is also very effective.