In the standard numerical anchoring paradigm, the influence of externally provided anchors on judgment is typically explained as a result of elaborate thinking (i.e., confirmatory hypothesis testing that selectively activates anchor-consistent information in memory). In contrast, theories of attitude change suggest that the same judgments can result from relatively thoughtful or non-thoughtful processes, with more thoughtful processes resulting in judgments that last longer over time and better resist future attempts at change. Guided by an attitudinal approach to anchoring, four studies manipulated participants’ level of cognitive load to produce relatively high versus low levels of thinking. These studies show that, although anchoring can occur under both high and low thought conditions, anchoring based on a higher level of thinking involves greater use of judgment-relevant background knowledge, persists longer over time, is more resistant to subsequent attempts at social influence, and is less likely to result from direct numeric priming.