diff --git a/stl/__init__.py b/stl/__init__.py
index 8d25cd4..b4b073b 100644
--- a/stl/__init__.py
+++ b/stl/__init__.py
@@ -1,6 +1,6 @@
 from stl.utils import terms_lens, lineq_lens, walk, tree, and_or_lens
 from stl.ast import dt_sym, t_sym
-from stl.ast import LinEq, Interval, NaryOpSTL, Or, And, F, G, ModalOp, Neg, Var
+from stl.ast import LinEq, Interval, NaryOpSTL, Or, And, F, G, ModalOp, Neg, Var, AtomicPred
 from stl.parser import parse
 from stl.synth import lex_param_project
 from stl.boolean_eval import pointwise_sat
diff --git a/stl/ast.py b/stl/ast.py
index 7a424ac..0e80291 100644
--- a/stl/ast.py
+++ b/stl/ast.py
@@ -13,6 +13,14 @@ str_to_varkind = {"x": VarKind.x, "u": VarKind.u, "w": VarKind.w}
 dt_sym = Symbol('dt', positive=True)
 t_sym = Symbol('t', positive=True)
 
+class AtomicPred(namedtuple("AP", ["id"])):
+    def __repr__(self):
+        return "{}".format(self.id)
+
+    def children(self):
+        return []
+
+
 class LinEq(namedtuple("LinEquality", ["terms", "op", "const"])):
     def __repr__(self):
         n = len(self.terms)
diff --git a/stl/boolean_eval.py b/stl/boolean_eval.py
index 2912f7f..f1f0772 100644
--- a/stl/boolean_eval.py
+++ b/stl/boolean_eval.py
@@ -5,6 +5,7 @@ from functools import singledispatch
 import operator as op
 
 import numpy as np
+import sympy as smp
 from lenses import lens
 
 import stl.ast
@@ -52,6 +53,11 @@ op_lookup = {
 }
 
 
+@pointwise_sat.register(stl.AtomicPred)
+def _(stl):
+    return lambda x, t: x[term.id][t]
+
+
 @pointwise_sat.register(stl.LinEq)
 def _(stl):
     op = op_lookup[stl.op]
diff --git a/stl/parser.py b/stl/parser.py
index 8d3bc75..81ccd51 100644
--- a/stl/parser.py
+++ b/stl/parser.py
@@ -21,7 +21,7 @@ from sympy import Symbol, Number
 from stl import ast
 
 STL_GRAMMAR = Grammar(u'''
-phi = (g / f / lineq / or / and / paren_phi)
+phi = (g / f / lineq / AP / or / and / paren_phi)
 
 paren_phi = "(" __ phi __ ")"
 
@@ -47,6 +47,8 @@ time = prime / time_index
 time_index = "[" "t" __ pm __ const "]"
 prime = "'"
 
+AP = ~r"[a-zA-z\d]+"
+
 pm = "+" / "-"
 dt = "dt"
 unbound = id "?"
@@ -145,6 +147,9 @@ class STLVisitor(NodeVisitor):
     def visit_pm(self, node, _):
         return Number(1) if node.text == "+" else Number(-1)
 
+    def visit_AP(self, node, _):
+        return ast.AtomicPred(node.text)
+
 
 def parse(stl_str:str, rule:str="phi") -> "STL":
     return STLVisitor().visit(STL_GRAMMAR[rule].parse(stl_str))