I shall review 20 years of research concerning the types of information that red-backed salamanders need in order to "decide" on appropriate social behavior patterns. Both male and female red-backed salamanders defend feeding territories on the forest floor in Virginia, using rocks and logs as territorial cover objects. I shall focus on how territorial residents respond to intruders and the types of information needed to shape those responses. For example, the resident might (1) threaten and then attack the intruder, (2) threaten but not attack (a bluff), (3) attack without prior threat (a sneak attack), (4) assume a submissive posture, (5) ignore the intruder, or (6) flee from the intruder. Field studies and laboratory experiments suggest that the behavior chosen is dependent on the (a) species, (b) sex, (c) size, and (D) tail condition of the intruder, as well as (e) the resident's familiarity with the intruder, (f) the food quality of the resident's territory, (g) the resident's social relationship (e.g., social monogamy) with the intruder, and (h) the previous polygamous experience of the intruder. This research indicates that red-backed salamanders have a far more complex social system than previously suspected for any species of amphibian.