diff --git a/CInterface/Library/SpeciesLibrary.cpp b/CInterface/Library/SpeciesLibrary.cpp
new file mode 100644
index 0000000..553a63f
--- /dev/null
+++ b/CInterface/Library/SpeciesLibrary.cpp
@@ -0,0 +1,8 @@
+#include "../../src/Library/Species/SpeciesLibrary.hpp"
+#include "../Core.hpp"
+using namespace PkmnLib::Library;
+
+export const PokemonSpecies* PkmnLib_PokemonLibrary_FindPreEvolution(const SpeciesLibrary* p,
+                                                                     const PokemonSpecies* species) {
+    return p->FindPreEvolution(species).GetRaw();
+}
\ No newline at end of file
diff --git a/src/Library/Species/SpeciesLibrary.cpp b/src/Library/Species/SpeciesLibrary.cpp
index aac3139..e5e49af 100644
--- a/src/Library/Species/SpeciesLibrary.cpp
+++ b/src/Library/Species/SpeciesLibrary.cpp
@@ -1 +1,20 @@
 #include "SpeciesLibrary.hpp"
+namespace PkmnLib::Library {
+    ArbUt::BorrowedPtr<const PokemonSpecies>
+    SpeciesLibrary::FindPreEvolution(const ArbUt::BorrowedPtr<const PokemonSpecies>& species) const noexcept {
+        if (_preEvolutionCache.Has(species)) {
+            return _preEvolutionCache[species];
+        }
+        for (auto& s : _values) {
+            auto pkmn = (PokemonSpecies*)s.second.get();
+            for (auto& evo : pkmn->GetEvolutions()) {
+                if (evo->GetNewSpecies() == species) {
+                    auto non_const = const_cast<SpeciesLibrary*>(this);
+                    non_const->_preEvolutionCache[species] = pkmn;
+                    return pkmn;
+                }
+            }
+        }
+        return nullptr;
+    }
+}
diff --git a/src/Library/Species/SpeciesLibrary.hpp b/src/Library/Species/SpeciesLibrary.hpp
index 675cffc..722d0d9 100644
--- a/src/Library/Species/SpeciesLibrary.hpp
+++ b/src/Library/Species/SpeciesLibrary.hpp
@@ -6,6 +6,9 @@
 
 namespace PkmnLib::Library {
     class SpeciesLibrary : public CreatureLib::Library::SpeciesLibrary {
+        ArbUt::Dictionary<ArbUt::BorrowedPtr<const PokemonSpecies>, ArbUt::BorrowedPtr<const PokemonSpecies>>
+            _preEvolutionCache;
+
     public:
         inline bool TryGet(const ArbUt::BasicStringView& name,
                            ArbUt::BorrowedPtr<const PokemonSpecies>& outSpecies) const {
@@ -26,6 +29,9 @@ namespace PkmnLib::Library {
         void Insert(const ArbUt::StringView& name, const PokemonSpecies* species) {
             CreatureLib::Library::SpeciesLibrary::Insert(name, species);
         }
+
+        ArbUt::BorrowedPtr<const PokemonSpecies>
+        FindPreEvolution(const ArbUt::BorrowedPtr<const PokemonSpecies>& species) const noexcept;
     };
 }