diff --git a/js/ai/src/generate.ts b/js/ai/src/generate.ts
index 5031cfb64..53523106a 100755
--- a/js/ai/src/generate.ts
+++ b/js/ai/src/generate.ts
@@ -16,6 +16,7 @@
 
 import {
   Action,
+  config as genkitConfig,
   GenkitError,
   runWithStreamingCallback,
   StreamingCallback,
@@ -431,7 +432,7 @@ export interface GenerateOptions<
   CustomOptions extends z.ZodTypeAny = z.ZodTypeAny,
 > {
   /** A model name (e.g. `vertexai/gemini-1.0-pro`) or reference. */
-  model: ModelArgument<CustomOptions>;
+  model?: ModelArgument<CustomOptions>;
   /** The prompt for which to generate a response. Can be a string for a simple text prompt or one or more parts for multi-modal prompts. */
   prompt: string | Part | Part[];
   /** Retrieved documents to be used as context for this generation. */
@@ -479,9 +480,25 @@ const isValidCandidate = (
   });
 };
 
-async function resolveModel(
-  model: ModelAction<any> | ModelReference<any> | string
-): Promise<ModelAction> {
+async function resolveModel(options: GenerateOptions): Promise<ModelAction> {
+  let model = options.model;
+  if (!model) {
+    if (genkitConfig?.options?.defaultModel) {
+      model =
+        typeof genkitConfig.options.defaultModel.name === 'string'
+          ? genkitConfig.options.defaultModel.name
+          : genkitConfig.options.defaultModel.name.name;
+      if (
+        (!options.config || Object.keys(options.config).length === 0) &&
+        genkitConfig.options.defaultModel.config
+      ) {
+        // use configured global config
+        options.config = genkitConfig.options.defaultModel.config;
+      }
+    } else {
+      throw new Error('Unable to resolve model.');
+    }
+  }
   if (typeof model === 'string') {
     return (await lookupAction(`/model/${model}`)) as ModelAction;
   } else if (model.hasOwnProperty('info')) {
@@ -537,7 +554,7 @@ export async function generate<
 ): Promise<GenerateResponse<z.infer<O>>> {
   const resolvedOptions: GenerateOptions<O, CustomOptions> =
     await Promise.resolve(options);
-  const model = await resolveModel(resolvedOptions.model);
+  const model = await resolveModel(resolvedOptions);
   if (!model) {
     throw new Error(`Model ${JSON.stringify(resolvedOptions.model)} not found`);
   }
diff --git a/js/core/src/config.ts b/js/core/src/config.ts
index 1381af8bf..65391d374 100644
--- a/js/core/src/config.ts
+++ b/js/core/src/config.ts
@@ -42,6 +42,10 @@ export interface ConfigOptions {
   logLevel?: 'error' | 'warn' | 'info' | 'debug';
   promptDir?: string;
   telemetry?: TelemetryOptions;
+  defaultModel?: {
+    name: string | { name: string };
+    config?: Record<string, any>;
+  };
 }
 
 class Config {
diff --git a/js/plugins/dotprompt/src/prompt.ts b/js/plugins/dotprompt/src/prompt.ts
index 12ff7600f..b0fc9c4a0 100644
--- a/js/plugins/dotprompt/src/prompt.ts
+++ b/js/plugins/dotprompt/src/prompt.ts
@@ -161,14 +161,6 @@ export class Dotprompt<Variables = unknown> implements PromptMetadata {
   private _generateOptions(
     options: PromptGenerateOptions<Variables>
   ): GenerateOptions {
-    if (!options.model && !this.model) {
-      throw new GenkitError({
-        source: 'Dotprompt',
-        message: 'Must supply `model` in prompt metadata or generate options.',
-        status: 'INVALID_ARGUMENT',
-      });
-    }
-
     const messages = this.renderMessages(options.input);
     return {
       model: options.model || this.model!,
diff --git a/js/samples/rag/src/index.ts b/js/samples/rag/src/index.ts
index ffc5b9882..890756b22 100644
--- a/js/samples/rag/src/index.ts
+++ b/js/samples/rag/src/index.ts
@@ -77,6 +77,12 @@ export default configureGenkit({
       },
     ]),
   ],
+  defaultModel: {
+    name: geminiPro,
+    config: {
+      temperature: 0.6,
+    },
+  },
   flowStateStore: 'firebase',
   traceStore: 'firebase',
   enableTracingAndMetrics: true,
diff --git a/js/samples/rag/src/prompt.ts b/js/samples/rag/src/prompt.ts
index fec34b3ab..c77c28130 100644
--- a/js/samples/rag/src/prompt.ts
+++ b/js/samples/rag/src/prompt.ts
@@ -15,7 +15,6 @@
  */
 
 import { defineDotprompt } from '@genkit-ai/dotprompt';
-import { geminiPro } from '@genkit-ai/vertexai';
 import * as z from 'zod';
 
 // Define a prompt that includes the retrieved context documents
@@ -23,7 +22,6 @@ import * as z from 'zod';
 export const augmentedPrompt = defineDotprompt(
   {
     name: 'augmentedPrompt',
-    model: geminiPro,
     input: z.object({
       context: z.array(z.string()),
       question: z.string(),