Bluegill Lepomis macrochirus support recreational fisheries across their geographic distribution. Harvest has historically been liberally regulated although research over the last 40 years has demonstrated favorable population response to more restrictive harvest. Bluegill fisheries in Kansas have commonly been unregulated but interest in developing quality fisheries prompted initiation of a 152-mm to 229-mm protected-slot length limit on Lepomis spp. in four small impoundments. These four regulated populations were examined with four control (i.e. no harvest restrictions) populations for patterns in relative abundance of quality-length fish (≥ 152 mm), length structure, and annual mortality pre-regulation and post-regulation. We observed no discernible population-level patterns in response to initiation of the harvest regulation. These findings suggest that the protected-slot length limit was ineffective at restructuring populations. Other actions (e.g., reduced creel limits, temporal or areal closures) should be considered if attempting to restructure Bluegill populations through harvest regulation. Alternatively, managers could explore non-regulatory actions (e.g., supplemental feeding, renovation) to elicit restructuring of Bluegill populations.