diff --git a/src/hearth/loop.py b/src/hearth/loop.py
index 314df7c..02fd7b5 100644
--- a/src/hearth/loop.py
+++ b/src/hearth/loop.py
@@ -54,6 +54,9 @@ def optimizer(self):
     def optimizer(self, optimizer):
         if isinstance(optimizer, LazyOptimizer) and not optimizer.initialized:
             optimizer.add_model(self.model)
+            # add parameters from loss function if any exist...
+            # this will be a Running object so we need to access inner function...
+            optimizer.add_model(self.loss_fn.fn)
         self._optimizer = optimizer
 
     def to(self, device: Union[torch.device, str]):
diff --git a/src/hearth/losses.py b/src/hearth/losses.py
index e4be045..7c77c54 100644
--- a/src/hearth/losses.py
+++ b/src/hearth/losses.py
@@ -393,3 +393,203 @@ def __init__(self, mask_target_value=-float('inf'), reduction: str = 'mean'):
     def forward(self, input: Tensor, target: Tensor) -> Tensor:
         mask = target != self.mask_target_value
         return nn.functional.mse_loss(input[mask], target[mask], reduction=self.reduction)
+
+
+class _AngularPenaltySoftMarginLoss(_BaseLoss):
+    """base class for angular penalty soft margin losses."""
+
+    def __init__(
+        self,
+        embedding_features: int,
+        n_classes: int,
+        scale: float,
+        margin: float,
+        eps: float = 1e-7,
+        reduction='mean',
+    ):
+        super().__init__(reduction=reduction)
+        self.embedding_features = embedding_features
+        self.n_classes = n_classes
+        self.scale = scale
+        self.margin = margin
+        self.eps = eps
+        self.weight = nn.Parameter(torch.FloatTensor(self.n_classes, self.embedding_features))
+        nn.init.xavier_uniform_(self.weight)
+
+    def _get_cos(self, inputs: Tensor) -> Tensor:
+        return nn.functional.linear(
+            nn.functional.normalize(inputs, p=2, dim=-1),
+            nn.functional.normalize(self.weight, p=2, dim=-1),
+        )
+
+    def _compute_unscaled_numerator(self, pos: Tensor):
+        return NotImplemented
+
+    def forward(self, inputs: Tensor, targets: Tensor) -> Tensor:
+        cos = self._get_cos(inputs)
+        n_classes = cos.shape[-1]
+        one_hot = torch.nn.functional.one_hot(targets, n_classes)
+        numerator = self.scale * self._compute_unscaled_numerator((cos * one_hot).sum(-1))
+        neg = cos.masked_fill(one_hot == 1, -float('inf'))
+        denominator = numerator.exp() + (self.scale * neg).exp().sum(-1)
+        err = -(numerator - torch.log(denominator))
+        return self._reduce(err)
+
+    def extra_repr(self) -> str:
+        out = [
+            f'embedding_features={self.embedding_features}',
+            f'n_classes={self.n_classes}',
+            f'scale={self.scale}',
+            f'margin={self.margin}',
+            f'eps={self.eps}',
+            f'reduction={self.reduction!r}',
+        ]
+
+        return ', '.join(out)
+
+
+class AdditiveAngularMarginLoss(_AngularPenaltySoftMarginLoss):
+    """AKA ArcFaceLoss.
+
+    Reference:
+       `Deng et al. : ArcFace: Additive Angular Margin Loss for Deep Face Recognition\
+            <https://arxiv.org/abs/1801.07698>`_
+
+    Note:
+        - this loss has weights and requires an optimizer.
+        - :attr:`margin` is already expressed in radians.
+
+    Args:
+        embedding_features: number of embedding features inputs are expected to be
+            (batch, embedding_features).
+        n_classes: number of classes in projection.
+        scale: Defaults to 64.0.
+        margin: margin in radians. Defaults to 0.5 (28.6 degrees).
+        eps: epsilon for clamping . Defaults to 1e-7.
+        reduction: batch reduction for this loss should be one of 'mean', 'sum', 'none'.
+            Defaults to 'mean'.
+
+    Example:
+        >>> import torch
+        >>> from hearth.losses import AdditiveAngularMarginLoss
+        >>> _ = torch.manual_seed(666)
+        >>>
+        >>>
+        >>> # this would be embeddings coming out of your model...
+        >>> emb = torch.normal(0, 1, size=(5, 128))
+        >>> targets = torch.randint(0, 10, size=(5,))
+        >>> loss = AdditiveAngularMarginLoss(128, 10)
+        >>> loss(emb, targets)
+        tensor(41.8191, grad_fn=<MeanBackward0>)
+    """
+
+    def __init__(
+        self,
+        embedding_features: int,
+        n_classes: int,
+        scale: float = 64.0,
+        margin: float = 0.5,
+        **kwargs,
+    ):
+        super().__init__(embedding_features, n_classes, scale=scale, margin=margin, **kwargs)
+
+    def _compute_unscaled_numerator(self, pos: Tensor) -> Tensor:
+        clipped = torch.clamp(pos, -1.0 + self.eps, 1 - self.eps)
+        return torch.cos(clipped.acos() + self.margin)
+
+
+class LargeMarginCosineLoss(_AngularPenaltySoftMarginLoss):
+    """AKA CosFaceLoss.
+
+    Reference:
+       `Wang et al. : CosFace: Large Margin Cosine Loss for Deep Face Recognition\
+            <https://arxiv.org/abs/1801.09414>`_
+
+    Note:
+        - this loss has weights and requires an optimizer.
+
+    Args:
+        embedding_features: number of embedding features inputs are expected to be
+            (batch, embedding_features).
+        n_classes: number of classes in projection.
+        scale: Defaults to 30.0.
+        margin: Defaults to 0.4.
+        eps: epsilon for clamping . Defaults to 1e-7.
+        reduction: batch reduction for this loss should be one of 'mean', 'sum', 'none'.
+            Defaults to 'mean'.
+
+    Example:
+        >>> import torch
+        >>> from hearth.losses import LargeMarginCosineLoss
+        >>> _ = torch.manual_seed(666)
+        >>>
+        >>>
+        >>> # this would be embeddings coming out of your model...
+        >>> emb = torch.normal(0, 1, size=(5, 128))
+        >>> targets = torch.randint(0, 10, size=(5,))
+        >>> loss = LargeMarginCosineLoss(128, 10)
+        >>> loss(emb, targets)
+        tensor(17.5245, grad_fn=<MeanBackward0>)
+    """
+
+    def __init__(
+        self,
+        embedding_features: int,
+        n_classes: int,
+        scale: float = 30.0,
+        margin: float = 0.4,
+        **kwargs,
+    ):
+        super().__init__(embedding_features, n_classes, scale=scale, margin=margin, **kwargs)
+
+    def _compute_unscaled_numerator(self, pos: Tensor) -> Tensor:
+        return pos - self.margin
+
+
+class SphereEmbeddingLoss(_AngularPenaltySoftMarginLoss):
+    """AKA SphereFaceLoss.
+
+    Reference:
+       `Liu et al. : SphereFace: Deep Hypersphere Embedding for Face Recognition\
+            <https://arxiv.org/abs/1704.08063>`_
+
+    Note:
+        - this loss has weights and requires an optimizer.
+
+    Args:
+        embedding_features: number of embedding features inputs are expected to be
+            (batch, embedding_features).
+        n_classes: number of classes in projection.
+        scale: Defaults to 64.0.
+        margin: Defaults to 1.35.
+        eps: epsilon for clamping . Defaults to 1e-7.
+        reduction: batch reduction for this loss should be one of 'mean', 'sum', 'none'.
+            Defaults to 'mean'.
+
+    Example:
+        >>> import torch
+        >>> from hearth.losses import SphereEmbeddingLoss
+        >>> _ = torch.manual_seed(666)
+        >>>
+        >>>
+        >>> # this would be embeddings coming out of your model...
+        >>> emb = torch.normal(0, 1, size=(5, 128))
+        >>> targets = torch.randint(0, 10, size=(5,))
+        >>> loss = SphereEmbeddingLoss(128, 10)
+        >>> loss(emb, targets)
+        tensor(44.7385, grad_fn=<MeanBackward0>)
+    """
+
+    def __init__(
+        self,
+        embedding_features: int,
+        n_classes: int,
+        scale: float = 64.0,
+        margin: float = 1.35,
+        **kwargs,
+    ):
+        super().__init__(embedding_features, n_classes, scale=scale, margin=margin, **kwargs)
+
+    def _compute_unscaled_numerator(self, pos: Tensor) -> Tensor:
+        clipped = torch.clamp(pos, -1.0 + self.eps, 1 - self.eps)
+        return torch.cos(self.margin * clipped.acos())