研究目的：本研究的目的，是以縱貫研究的方式探討自閉症類疾患兒童自學齡前期至學齡期的臨床診斷穩定度、自閉症狀嚴重度變化、適應行為型態與其變化、內外化行為。 研究方法：本研究納入28名自閉症類疾患與18位非自閉症類疾患，於三個時間點進行評估：時間點一平均生理年齡為2歲半、時間點二為4歲、時間點三為9歲半。本研究分析三個時間點之臨床診斷穩定度以及後兩個時間點之評估資料。症狀嚴重度方面，以自閉症診斷會談問卷修訂版之晤談評估；適應行為方面，以文蘭適應行為量表第二版評估；認知功能方面，時間點二時以穆林發展量表評估，時間點三時使用魏氏兒童智力量表第四版評估；內外化行為方面，時間點三時以阿肯巴克實證衡鑑系統中的兒童行為檢核表評估。 研究結果：本研究結果顯示，自閉症類疾患從學齡前期至學齡期的臨床診斷穩定度高，若分亞型來看，自閉性疾患的診斷穩定度比其他未註明之廣泛性發展疾患高。症狀嚴重度方面，學齡期時自閉症類疾患兒童的溝通、侷限及重複刻板行為有顯著改善，社交行為亦有改善趨勢。適應行為方面，學齡前期及學齡期皆未發現自閉症類疾患與非自閉症類疾患之表現型態有差異，兩組在社會化領域的表現皆較其他領域來得差。自閉症類疾患的適應行為於學齡期時，年齡當量顯著增加，但社會化適應行為標準分數反而退步；進一步以認知功能分組檢視，則發現高功能自閉症類疾患在日常生活技巧與社會化領域的進步幅度顯著較多。內外化行為方面，學齡期時自閉症類疾患個案的退縮/憂鬱分量尺與社會問題分量尺之分數高於非自閉症類疾患，且自閉症類疾患在退縮/憂鬱、社會問題、注意力問題等三個分量尺上，皆有超過一半的個案達到邊緣範圍以上之分數；未發現內外化行為與自閉症狀嚴重度之間的相關。 結論：自閉症類疾患兒童到了學齡期大部分仍維持臨床診斷，顯示其自閉特徵仍然穩定存在，不過症狀嚴重度的整體趨勢會隨著年紀改善；但若以個體差異來看，每位個案進步的程度呈現高異質性，每位個案症狀改變的程度可能不同。自閉症類兒童的社會化適應行為從學齡前期至學齡期皆為其弱項，雖適應行為會隨著年齡進步，但社會化適應行為仍追不上同儕程度；高功能自閉症類疾患兒童的適應行為在日常生活技巧與社會化領域的進步幅度顯著較多，可能與認知功能有關。內外化行為方面，自閉症類疾患兒童的退縮/憂鬱問題、社會問題、注意力問題較多，但與症狀嚴重度無關。 / Purposes: The purpose of this longitudinal study was to examine the stability of clinical diagnosis, symptom severity, adaptive function and enternal/external behavior from toddler to school age in children with autism spectrum disorders (ASDs). Methods: Twenty eight children diagnosed with ASDs and eighteen children with Non-ASDs participated at time 1 (mean chronological age was 2.5 years old), and then followed at time 2 (mean chronological age was 4 years old) and at time 3 (mean chronological age was 9.5 years old). This study examines the stability of clinical diagnosis from time 1 to time 3, and analyze the measurement data between time 2 and time 3. Autism Diagnostic Interview-Revised (ADI-R) was used to measure autistic symptom severity at time 2 and time 3; Vineland Adaptive Behavior Scales-II (VABS-II) was used to measure daily adaptive behavior at time 2 and time 3; Mullen Scale of Early Learning (MSEL) or Wechsler intelligence scale for children-Fourth Edition (WISC-IV) was used to measure cognitive function at two time points; Child Behavior Checklist for Ages 6-18 (CBCL/6-18) was used to measure enternal and external behavior at time 3. Results: The stability of clinical diagnosis was high from toddler age to school age, and the stability of Autistic Disorder was higher than Pervasive Developmental Disorder Not Otherwise Specified. The ADI-R scores of communication domain, repetitive and stereotyped behavior domain were decreased at school age, while reciprocal social interaction domain was also declined but no significant difference. All domains of VABS-II standard score were no significant difference between ASDs and Non-ASDs at two time point, and the score of social domain was worst in both two groups. The VABS-II standard score of social domain was reduced although the age equivalent was increased at school age, and the standard score of other domains were no significant difference between the two time points but all age equivalents were improved at school age. Dividing ASDs to high-function ASDs and low-function ASDs to analyze the growth rate of adaption behaviors, the results indicated that the growth rate of adaption behaviors were higher in high-function ASDs at daily skill domain and social domain. Children with ASDs had significant higher scores on Withdrawn/Depressed scale and Social Problem scale than Non-ASDs in CBCL, and over 50 percent of ASDs scored above the borderline range at Withdrawn/Depressed scale, Social Problem scale and Attention Problem scale. In addition, there were no significant correlations between CBCL and ADI-R. Conclusions: In summary, the study showed that most of ASDs sustained the clinical diagnosis from preschool age to school age, however, the autistic symptom severity was declined. Additionally, the improvement of symptom severity of individual ASDs was high variability. The social adaptive behavior was worst in both toddler age and school age in ASDs. Although these children with ASD developed some of adaptive behaviors in the school age, the magnitude of improvement couldn’t equal to the change of their chronological age, especially in socialization domain. The growth rate of daily skill domain and social domain were higher in high-function ASDs than low-function ASDs, might associated with cognitive function. More Children with ASDs had withdrawn/depressed problem, social problem and attention problem, but there were not related to autistic symptom severity.