diff --git a/cpm/models.py b/cpm/models.py
index 93fc6b2..4136abf 100644
--- a/cpm/models.py
+++ b/cpm/models.py
@@ -25,6 +25,8 @@ def __init__(self, matrix: list[list[Optional[float]]], columns: list[str], inst
         if instigator not in ['row', 'column']:
             raise ValueError('instigator argument needs to be either "row" or "column".')
 
+        self.validate_matrix()
+
     @staticmethod
     def clean_matrix(matrix) -> list[list[float]]:
         cleaned_matrix = []
@@ -42,6 +44,14 @@ def clean_matrix(matrix) -> list[list[float]]:
 
         return cleaned_matrix
 
+    def validate_matrix(self):
+        try:
+            assert len(self.matrix) == len(self.columns)
+            for row in self.matrix:
+                assert len(row) == len(self.columns)
+        except AssertionError:
+            raise ValueError('Matrix dimensions are inconsistent with provided columns.')
+
     def __str__(self):
         return f'{self.columns}\n{self.matrix}'
 
@@ -184,6 +194,9 @@ def __init__(self, start_index: int, target_index: int, dsm_impact: DSM, dsm_lik
             start_index = target_index
             target_index = temp
 
+        if len(dsm_impact.matrix) != len(dsm_likelihood.matrix):
+            raise ValueError('Impact and Likelihood matrices need to have the same dimensions.')
+
         self.dsm_impact: DSM = dsm_impact
         self.dsm_likelihood: DSM = dsm_likelihood
         self.start_index: int = start_index
diff --git a/tests/test_input_validation.py b/tests/test_input_validation.py
new file mode 100644
index 0000000..ec0f388
--- /dev/null
+++ b/tests/test_input_validation.py
@@ -0,0 +1,54 @@
+import pytest
+from cpm.models import ChangePropagationTree, DSM
+from cpm.parse import parse_csv
+from cpm.utils import calculate_risk_matrix
+
+
+def test_throws_if_dsm_instigator_mismatch_1():
+    dsm_p = parse_csv('./tests/test-assets/dsm-cpx-probs.csv', instigator="row")
+    dsm_i = parse_csv('./tests/test-assets/dsm-cpx-imps.csv')
+
+    with pytest.raises(ValueError):
+        calculate_risk_matrix(dsm_i, dsm_p, search_depth=4)
+
+
+def test_throws_if_dsm_instigator_mismatch_2():
+    dsm_p = parse_csv('./tests/test-assets/dsm-cpx-probs.csv', instigator="row")
+    dsm_i = parse_csv('./tests/test-assets/dsm-cpx-imps.csv')
+
+    with pytest.raises(ValueError):
+        ChangePropagationTree(0, 4, dsm_i, dsm_p)
+
+
+def test_throws_if_dsm_incomplete():
+    mtx = [
+        [0.1, 0.2, 0.3],
+        [0.4, 0.5, 0.6],
+        [0.7, 0.8, 0.9],
+    ]
+    cols = ["a", "b", "c", "d"]
+    with pytest.raises(ValueError):
+        dsm = DSM(mtx, cols)
+
+
+def test_throws_if_dsm_size_mismatch():
+    cols_p = ["a", "b", "c"]
+    mtx_p = [
+        [0.1, 0.2, 0.3],
+        [0.4, 0.5, 0.6],
+        [0.7, 0.8, 0.9],
+    ]
+    cols_i = ["a", "b", "c", "d"]
+    mtx_i = [
+        [0.1, 0.2, 0.3, 0.4],
+        [0.4, 0.5, 0.6, 0.7],
+        [0.7, 0.8, 0.9, 0.10],
+        [0.11, 0.12, 0.13, 0.14]
+    ]
+
+    dsm_p = DSM(mtx_p, cols_p)
+    dsm_i = DSM(mtx_i, cols_i)
+
+    with pytest.raises(ValueError):
+        # If DSMs are of different size, then input validation should prevent execution.
+        ChangePropagationTree(0, 2, dsm_i, dsm_p)
diff --git a/tests/test_propagation.py b/tests/test_propagation.py
index 75926bd..1564da6 100644
--- a/tests/test_propagation.py
+++ b/tests/test_propagation.py
@@ -122,26 +122,34 @@ def test_probability_calculation():
 def test_dsm_input_robustness():
     instigator = 'column'
     cols = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
+    # Purposefully poorly formatted input matrix
     mtx_i = [['-', '0', 0.3, None, None, None, 0.7, 0],
              [None, '-', 0, 0.4, 0.5, None, None, None],
-             ["0.1", 0, '-', '', '', '', 0.8],
-             [0, 0, 0, 'D', 0, 0.7, 0],
+             ["0.1", 0, '-', '', '', '0.6', 0, 0],
+             [0, 0, 0, 'D', 0, 0, None, 0.8],
              [0, 0, 0, 0, None, None, 0.7, 0],
              ['0.1', '0.2', 0, 0, None, 'F', 0.7, 0],
              [0, 0, 0, 0, 0, 0.6, 99, 0],
              [0, 0, 0.3, 0.4, 0, 0, 0, 'H']]
 
     dsm_i = DSM(mtx_i, cols, instigator)
+    # Purposefully poorly formatted input matrix
+    mtx_l = [[None, None, 0.1, None, None, None, 0.1, None],
+             [None, 'B', 0, 0.2, "0.2", 0, 0, None],
+             ["0.3", None, 'C', None, None, 0.3, None, 0],
+             [0, 0, 0, "D", 0, 0, 0, 0.4],
+             [0, 0, 0, 0, "E", 0, 0.5, 0],
+             [0.6, 0.6, None, None, None, "F", "0.6", None],
+             [None, None, None, None, None, 0.7, "G", 0],
+             [0, 0, 0.8, 0.8, 0, 0, 0, "H"]]
+
+    dsm_p = DSM(mtx_l, cols, instigator)
 
-    dsm_l = [[],
-             [],
-             [],
-             [],
-             [],
-             [],
-             [],
-             []]
-
+    dsm_r = parse_csv('./tests/test-assets/dsm-cpx-answers-risks.csv')
+    res_mtx = calculate_risk_matrix(dsm_i, dsm_p, search_depth=4)
 
-def test_input_throws_if_dsm_instigator_mismatch():
-    pass
+    for i, col_i in enumerate(dsm_r.columns):
+        for j, col_j in enumerate(dsm_r.columns):
+            if i == j:
+                continue
+            assert abs(res_mtx[i][j] - dsm_r.matrix[i][j]) < 0.001, f"Failed for index i={i} (row {col_i}), j={j} (col {col_j})"