ABSTRACTAccording to the constant growth model and perceived finance theory, the cost of new external equity exceeds the cost of retained earnings due to flotation costs and underpricing. Carlson and Dietz [1] have recently argued that the constant growth model is operationally inadequate whenever the net proceeds from the issuance of a new share differ from book value. Specifically, they contend that the cost of new external equity is less than the cost of retained earnings whenever the net proceeds from a new share exceed book value. We show that these conclusions stem from an error in interpretation and therefore that the constant growth model is valid regardless of the relationship between market prices and book value.