We　demonstrate　a　mode　of　thin　film　growth　in　which　amorphous　islands　crystallize　into　highly　oriented　platelets.　A　cascade　of　crystallization　is　observed,　in　which　platelets　growing　outward　from　a　central　nucleation　point　impinge　on　neighboring　amorphous　islands　and　provide　a　seed　for　further　nucleation.　Through　control　of　growth　parameters,　it　is　possible　to　produce　high　quality　thin　films　which　are　well　suited　to　the　formation　of　organic　transistors.　We　demonstrate　this　through　the　fabrication　of　rubrene　thin　film　transistors　with　high　carrier　mobility.