Many advertised products are established and have little quality variation. For these products advertising signaling explanations are unconvincing. We develop a coordination model of advertising with consumers observing ads probabilistically and never observing advertising levels. Consumers who fail to see an ad for a product believe it will likely have low sales and so be of low value. Firms advertise to avoid these beliefs. The model’s predictions on advertising, market share, and profitability are consistent with observed outcomes. The model produces the time series behavior for prices and market share observed in the data and not available from existing coordination models.