diff --git a/src/cobra/core/compartment.py b/src/cobra/core/compartment.py
new file mode 100644
index 000000000..d308dee0d
--- /dev/null
+++ b/src/cobra/core/compartment.py
@@ -0,0 +1,176 @@
+"""Define the group class."""
+
+from typing import Iterable, Optional, Union, List, FrozenSet
+from warnings import warn
+
+from .dictlist import DictList
+from .group import Group
+from .. import Metabolite, Reaction, Model
+
+
+class Compartment(Group):
+    """
+    Manage compartments via this implementation of the SBML group specification.
+
+    `Compartment` is a class for holding information regarding a bounded space in
+    which species are located. You can think of it as a location in a model,
+    usually representing organelles like the Endoplasmic Reticulum (ER).
+
+    Parameters
+    ----------
+    id : str
+        The identifier to associate with this group
+    name : str, optional
+        A human readable name for the group
+    members : iterable, optional
+        A DictList containing references to cobra.Model-associated objects
+        that belong to the group. Members should be metabolites or genes, where
+        reactions are inferred from metabolites.
+    dimensions: float, optional
+        Compartments can have dimensions defined, if they are volume (3 dimensions) or
+        2 (a two-dimensional compartment, a surface, like a membrane). In theory, this
+        can be 1 or 0 dimensions, and even partial dimensions (fractal dimensions for
+        trees and vessels). For almost every application in constraint based modeling
+        this will be an integer. The number of dimensions influences the size and
+        units used.
+    """
+    def __init__(self, id: str, name: str = "", members: Optional[Iterable] = None,
+                 dimensions: Optional[float] = None):
+        """Initialize the Compartment object.
+
+         id : str
+            The identifier to associate with this group
+        name : str, optional
+            A human readable name for the group
+        members : iterable, optional
+            A DictList containing references to cobra.Model-associated objects
+            that belong to the group.
+        dimensions: float, optional
+            Compartments can have dimensions defined, if they are volume (3 dimensions) or
+            2 (a two-dimensional compartment, a surface, like a membrane). In theory, this
+            can be 1 or 0 dimensions, and even partial dimensions. The number of
+            dimensions influences the size and units used.
+
+        Raises
+        ------
+        TypeError if given anything other than metaoblites or reactions.
+        """
+        super().__init__(id, name, members)
+        for x in members:
+            if not isinstance(x, (Metabolite, Reaction)):
+                raise(TypeError, f"Compartments should only have reactions or "
+                                 f"metabolites as members. {x} is a {type(x)}.")
+        self._members = DictList() if members is None else DictList(members)
+        self._compartment_type = None
+        self.__delattr__("kind") # Compartments don't have kind
+        # self.model is None or refers to the cobra.Model that
+        # contains self
+        self._dimensions = dimensions
+        self._model = None
+
+    def add_members(self, new_members: Union[str, Metabolite, Reaction,
+                                             List[Union[Reaction, Metabolite]]]) -> None:
+        """Add objects to the compartment.
+
+        Parameters
+        ----------
+        new_members : list or str or Metabolite or Reaction
+            A list of cobrapy Metabolites or Genes to add to the group. If it isn't a
+            list a warning will be raised.
+            If it isn't a metaoblite or a gene, an error will be raised.
+
+        Raises
+        ------
+        TypeError - if given any object other than Metaoblite or Reaction
+        """
+        if isinstance(new_members, str) or hasattr(new_members, "id"):
+            warn("need to pass in a list")
+            new_members = [new_members]
+
+        #TODO - add some filtering on type. What happens if given a string? Check
+        # DictList and groups.
+
+        self._members.union(new_members)
+        for _member in new_members:
+            _member._compartment = self
+
+    def remove_members(self, to_remove: list) -> None:
+        """Remove objects from the group.
+
+        Parameters
+        ----------
+        to_remove : list
+            A list of cobra objects to remove from the group
+        """
+        if isinstance(to_remove, str) or hasattr(to_remove, "id"):
+            warn("need to pass in a list")
+            to_remove = [to_remove]
+
+        for member_to_remove in to_remove:
+            self._members.remove(member_to_remove)
+            member_to_remove._compartment = None
+
+    @property
+    def metabolites(self) -> DictList[Metabolite]:
+        """Return the metaoblites in the compartment, if any.
+
+        Returns
+        -------
+        DictList:
+            DictList of metaoblites if any are present in the compartment. If there are
+            no metaoblties, will return an empty DictList.
+
+        """
+        return self._members.query(lambda x: isinstance(x, Metabolite))
+
+    @property
+    def inferred_reactions(self) -> FrozenSet[Reaction]:
+        """Return the reactions whose metabolites are in the compartment.
+
+        This is returned as a FrozenSet of reactions for each metabolite in the
+        compartment, if any.
+
+        Returns
+        -------
+        FrozenSet of cobra.Reactions
+            Reactions that have metabolites that belong to this compartment.
+
+        Returns
+        -------
+        FrozenSet of cobra.Reactions
+            Reactions that have metabolites that belong to this compartment.
+        """
+        rxn_set = set()
+        for met in self.metabolites:
+            rxn_set.update(met._reactions)
+        return frozenset(rxn_set)
+
+    @property
+    def assigned_reactions(self) -> FrozenSet[Reaction]:
+        """Return the reactions who were assigned to this compartment.
+
+        This is returned as a FrozenSet of reactions for each metabolite in the
+        compartment, if any.
+
+        Returns
+        -------
+        FrozenSet of cobra.Reactions
+            Reactions that have metabolites that belong to this compartment.
+
+        Returns
+        -------
+        FrozenSet of cobra.Reactions
+            Reactions that were assigned to this compartment, if any.
+        """
+        return frozenset(self._members.query(lambda x: isinstance(x, Reaction)))
+
+    def __contains__(self, member: Union[Metabolite, Reaction]):
+        return self.members.__contains__(member)
+
+    def merge(self, other):
+        warn("Not implemented yet")
+        return
+
+    def copy(self, new_id: str, new_model: Model, new_name: Optional[str] = None):
+        warn("Not implemented yet")
+        return
diff --git a/src/cobra/core/metabolite.py b/src/cobra/core/metabolite.py
index 2376f6945..fe5a0805a 100644
--- a/src/cobra/core/metabolite.py
+++ b/src/cobra/core/metabolite.py
@@ -51,7 +51,7 @@ def __init__(
         formula: Optional[str] = None,
         name: Optional[str] = "",
         charge: Optional[float] = None,
-        compartment: Optional[str] = None,
+        compartment: Optional["Compartment"] = None,
     ) -> None:
         """Initialize Metaboblite cobra Species.
 
@@ -71,7 +71,8 @@ def __init__(
         super().__init__(id=id, name=name)
         self.formula = formula
         # because in a Model a metabolite may participate in multiple Reactions
-        self.compartment = compartment
+        self._compartment = compartment
+        self.compartment = self._compartment.id
         self.charge = charge
 
         self._bound = 0.0
diff --git a/src/cobra/core/reaction.py b/src/cobra/core/reaction.py
index 4f78cbf14..a1e64afd0 100644
--- a/src/cobra/core/reaction.py
+++ b/src/cobra/core/reaction.py
@@ -23,6 +23,7 @@
 )
 from warnings import warn
 
+from .compartment import Compartment
 
 if TYPE_CHECKING:
     from optlang.interface import Variable
@@ -111,6 +112,8 @@ def __init__(
         # contains self
         self._model = None
 
+        self._compartment = None
+
         # from cameo ...
         self._lower_bound = (
             lower_bound if lower_bound is not None else config.lower_bound
@@ -1417,9 +1420,12 @@ def compartments(self) -> Set:
         set
             A set of compartments the metabolites are in.
         """
-        return {
-            met.compartment for met in self._metabolites if met.compartment is not None
-        }
+        if self._compartment:
+            return set(self._compartment.id)
+        else:
+            return {
+                met.compartment for met in self._metabolites if met.compartment is not None
+            }
 
     def get_compartments(self) -> list:
         """List compartments the metabolites are in.
@@ -1434,6 +1440,18 @@ def get_compartments(self) -> list:
         warn("use Reaction.compartments instead", DeprecationWarning)
         return list(self.compartments)
 
+    @property
+    def location(self) -> Optional[Compartment]:
+        """Get assigned compartment, if any.
+
+        Returns
+        -------
+        Compartment
+            Gets the compartment this reaction was explicitly assigned to, if one
+            exists. If no compartment was assigned, return None.
+        """
+        return self._compartment
+
     def _associate_gene(self, cobra_gene: Gene) -> None:
         """Associates a cobra.Gene object with a cobra.Reaction.
 
diff --git a/src/cobra/core/species.py b/src/cobra/core/species.py
index 68b095d9c..4ff106123 100644
--- a/src/cobra/core/species.py
+++ b/src/cobra/core/species.py
@@ -45,6 +45,7 @@ def __init__(
         self._model = None
         # references to reactions that operate on this species
         self._reaction = set()
+        self._comparment = None
 
     @property
     def reactions(self) -> FrozenSet: