Although Possibility Haecceitism requires quantification over possibilities, it remains silent about possible worlds. But, for most realists about possible worlds, quantification over maximal possibilities requires or is simply equivalent to quantification over possible worlds. Typically, such realist views of possible worlds identify each maximal possibility with a unique possible world and non-maximal possibilities with sets of possible worlds. And, while views that reduce possibilities to possible worlds can employ Possibility Haecceitism to express haecceitism, some might be tempted to interpret haecceitism as a thesis about qualitatively indiscernible worlds. Such a view would attempt to formulate haecceitism as the following thesis: